All For One/Synopsis

Early life
When they were kids, the Shigaraki brothers used to read Captain Hero comics. The younger brother, Yoichi, was a fan of the titular protagonist, Captain Hero, while the older brother was a fan of Captain Hero's nemesis, the Demon King. The older brother read only to Volume 3 of the series, but stopped because he didn't like the cliched ending. Since then, he dreamt of being a demon king and creating the world just like the comics.

The introduction of Quirks to the world led to a period of societal collapse and an age of upheaval. During this time, the older brother obtained an overwhelmingly powerful Quirk known as All For One, which he proceeded to name himself after, and rose through the ranks in Japan. He decided to take advantage of the chaos, stole many Quirks and attaining immense power and influence. Using his incredible might, the man gathered and unified dozens of people under his command. He then manipulated the people he gathered like pawns to further his plans and eventually became Japan's ruler.

It's suggested that he ruled from the shadows, as most of his actions in the present day are only known as rumors on the internet. He also started grooming other powerful individuals who he deemed to have a lot of potential, such as Gigantomachia, who became his personal bodyguard, though when this happened is unknown.

All For One's younger brother, Yoichi Shigaraki, opposed his evil as All For One tried to show him that he was helping people by ridding those who believed themselves plagued and giving strength to those who were helpless. Yoichi saw through All For One's claims, deeming that he is only trying to amass people who owe him into servitude. All For One defended this by stating his Quirk is able to return order to the world that has lost its humanity at the hands of Quirks.

Yoichi refuses to give in to his brother's manipulative statements and tried to rebel but was stopped by All For One's personal bodyguard. All For One berated his brother for not having a Quirk but says that he still loves him as he is his only family and imprisoned him rather than kill him.

When All For One visited his captive brother, he saw how thin he became due to not eating. All For One tells his brother about how a group who refused to join him were killed, simply because his followers interpreted his desires as instructions to kill them. Yoichi was disgusted and voiced his defiance. All For One then used his Quirk to forcibly give his little brother a Quirk that could stockpile power in order to make him submit to him but also to make him more powerful. What no one knew at the time is that Yoichi already had an innate Quirk which could only be transferred to others. The two Quirks mutated, blending together, and would later become known as One For All.

It was during this time when he met Kyudai Garaki. Kyudai theorized the "Quirk Singularity", according to which someday Quirks will become so powerful that they will be uncontrollable, but society scoffed at this theory, so he disappeared from the public eye. However, possibly due to the nature of his own Quirk, All For One believed his theory and lended Kyudai his aid. Since then, Kyudai has been working for All For One. As a gift of loyalty and appreciation, Kyudai duplicated his Life Force Quirk, and gave his original Quirk to All For One, keeping the duplicate. Thanks to this, both he and All For One continue to live to this day.

Battle against the One For All users
Yoichi was not strong enough to defeat his brother even with his new Quirk, so he passed it on to the next generation in the hopes that one day One For All would be strong enough to defeat his older brother. All For One fought and killed nearly all of these successors, including attempting to steal One For All from the fifth and sixth users, but failed due to its inherent willpower and refusal to submit to All For One, as the Quirk continued to be passed on.

Several generations later, the seventh torchbearer, Nana Shimura with her pupil and eighth bearer Toshinori Yagi, and her friend Sorahiko Torino, tried to stop him. However, despite their best efforts, All For One still overwhelmed them. Aware that they could not defeat him, Nana pushed Toshinori out of harms way and Gran Torino fled with Toshinori as the young man cries for his master. Nana departed some final words of encouragement onto Toshinori before standing against All For One one last time. The villain thanked Nana for providing quality comedy and finished her off with a large flash of black lightning.

Many years later, after Tenko Shimura accidentally murdered his family during the awakening of his Quirk, All For One met him under a bridge and granted him a home and safety. He provided Tenko a home and guidance to overcome his violent urges. Kyudai entered the room with Tenko's family's dissected hands, causing the boy to suffer a mental breakdown remembering his family.

Kyodai questioned whether All For One should modify Tenko. All For One replied no, and that he would teach him how to take his feelings and frustrations, and give them purpose. All For One told Tenko that he had an impulse to destroy that couldn't be controlled. He assured him that the impulse didn't have to be controlled, nor was it necessarily a bad thing.

One day, Tenko got into a fight with two punks. He was going to fight back and uses the Decay on them but backed down. Later, he threw a tantrum while All For One tried to console the young Tenko, telling him that he should act as his heart commands, otherwise he would suffer for it. He explained that conscience, morals, and ethics were all fabrications, intended to restrain people like them. He asked Tenko one more time what he would like to do. Tenko replied that he wanted to kill the two street thugs, noting that he couldn't hold back his feelings anymore. He disintegrated one of the hands, and All For One smiled, and told him to try his best.

On a rooftop nearby, All For One and Kyudai watched Tenko murdering the street punks. Garaki expressed surprise at the events, saying he thought that Tenko had lost his memories. All For One corrected him, noting that the memories were still there, just shut away. He noted that his family's hands would serve to restrain him, keeping all but his negative emotions suppressed. He saw that Tenko is subconsciously keeping his Quirk in check. Smiling, All For One expressed pride in seeing Tenko's first step down the path to becoming the Symbol of Fear, and said that he will cultivate and encourage him on the journey.

Later, All For One awarded Tomura five new dissected hands. Four belong to the two thugs he killed, and he explains that the fifth hand is a small bonus to make up for the one he destroyed earlier. He asked Tenko to put on all the new hands, and rechristened him "Tomura Shigaraki" as Tomura means "to mourn" and Shigaraki is his own surname. After this, All For One began grooming Tomura as his successor and as the new Symbol of Terror, knowing that this growing raw hatred of his could be used to finally steal One For All. All For One was also aware that Tomura was suppressing his memories and his Quirk.

The threat of All Might
Toshinori Yagi, Nana's disciple, returned to Japan after a long absence in the United States, and soon became All Might, Japan's No. 1 hero and symbol of peace. All For One attempted to stop All Might with his soldiers and accomplices, though All Might was able to best all of them, and with his actions, All Might began to dismantle All For One's criminal empire.

All For One began to suspect that he would eventually be defeated, so he took several contingency measures in case this would happen, such as sending Gigantomachia away into the woods for hiding. Likewise, in collaboration with Kyudai Garaki, All For One duplicated his own Quirk, with the intention of transferring it to Tomura when the time comes. In the meantime, Kyudai utilized this duplicate of All For One for various experiments.

At some point, All For One recovered the body of the deceased Oboro Shirakumo, and had Kyudai turn him into the Nomu called Kurogiri, who served as their close confidant and assistant.

One of All For One and Kyudai's experiments involved a young nameless boy they took in known as "Experiment Number 6." He suffered from a case of agnosia, having absolutely no awareness of his own self, whether due to a brain defect or childhood trauma. While Kyudai believed his state to be unfit as a pupil, All For One disagreed, seeing his "blank slate" as someone they can shape like a wad of clay into whatever form he desires, potentially even the twisted entity they seek.

All For One showed him videos and visuals of many Pro Heroes, telling him to choose whatever Quirk and Hero most interested him, and let that take his form. Number 6 chose O'Clock, who All For One complimented him on, telling him to visualize him as his mentor, and that he is the form he's meant to take.

The Underground Masquerade
A few years later, in the city of Osaka, All For One organized an illegal fighting event known as the Underground Masquerade. The event helped him move illegal drugs, test different variants of Quirk-Boosting drugs, and search for interesting Quirks worth stealing. His activities attracted the attention of the Pro Hero O'Clock, who infiltrated the tournament by posing as a fighter, obtaining evidence of drug trafficking. It also attracted a young Rumi Usagiyama, although she was more interested in fighting, defeating everyone who dared to face her.

All For One, who had been watching the fights from the security room, decided to harvest some Quirks. He released a gas that empowers the Quirks, making those who breathe it go on a rampage. To prevent anyone from fleeing, All For One deployed his subordinates, including a Hooded Man, and with the help of Kurogiri and his Warp Gate, he steals those Quirks that interest him.

All For One was especially eager to get hold of O'Clock's Quirk, Overclock, to give to Number 6. The hero allied with Rumi and Kendo Rappa, one of the underground fighters, to escape from there. Their escape was interrupted by the Hooded Man, leading to a battle between them. All For One was annoyed at being unable to see a clear view of the battle, due to most of the security cameras being destroyed, as well as the panicking spectators getting in the way. He contemplates clearing the arena himself, but Kurogiri disagrees as he believes any further escalation might summon All Might to the place, further irritating All For One. He decides to let the situation settle on its own.

When realizing that the Hooded Man was too difficult a foe to defeat by his own means, O'Clock put in motion an emergency plan, which consisted of Rumi escaping and warning his allies outside to request the assistance of All Might. The plan worked, and All Might immediately left his hero office to help out in Osaka. Kurogiri informed All For One that since All Might is on his way, they should retreat so as not to lose their valuable test subjects, as well as O’Clock, but All For One, annoyed that he couldn’t watch the fight between O’Clock and the Hooded Man, instead requested Kurogiri to assist him in buying some time.

After explaining to his Kurogiri the dichotomy between heroes and villains, All For One places his hand on several of the unconscious individuals, utilizing his Quirk on each of them to boost their powers, transforming them into violent villains who rampaged the city streets. All For One was satisfied with the results, because even All Might would waste time protecting everyone and reestablishing order, but Kurogiri tells him that he has gone too far with his action, because the incident would serve as a clue that leads back to them. All For One didn't care about it, arguing that it is a risk well worth the chance to get the Overclock Quirk.

All Might shows up and defeats all the villains in the blink of an eye. Kurogiri relents that All Might's actions barely bought them anytime, but All For One gleefully responds that it bought them "three seconds", more than enough to be able to get Overclock. However, the unexpected intervention of Rumi, who returned to help fight the Hooded Man, spoiling the plan, Which leaves him frustrated and displeased. With All Might closing in, Kurogiri uses his Quirk to quickly retrieve the Hooded Man.

Once in the hideout, Hood rampages around, yelling that he can still fight, when he is stopped and restrained by All For One. He expressed his disappointment on him, as his strength, agility, and regeneration had greatly weakened after just a few minutes of battle, initially believing his martial arts skills would’ve got the job done, but that his commitment to brawling messes with his new Shape-Shifting ability.

Using his Quirks to shut him down, All For One tells Kurogiri to transport him over to the doctor for further modifications. Despite the failure, All For One keeps calm and reflects that he can be patient, since every step leads him closer to All Might, though still states that getting his hands on Overclock would’ve furthered the cause, saying that it will be his eventually and he already knows how he’ll put it to use.

The Fall of All For One
All Might eventually fought and critically injured All For One, but he similarly received a debilitating wound in the process. Incapacitated by his defeat, All For One went into hiding as he attempted to heal from his injuries, having Gigantomachia and Kyudai track down useful Quirks to help him recover. During this period of time, All For One stole a Super Regeneration Quirk, which he believed would be of use to help his condition, however learned that due to most of his wounds having cauterized, it had little effect on him.

My Hero Academia: Vigilantes
At some point shortly after being injured, the hero O'Clock infiltrated one of his lairs, coming face to face with the Villain, who snatched his Quirk Overclock and wounded his face, leaving a distinctive scar. He would then give Overclock to Number 6 to let his transformation process begin.

During this period of time, All For One began to conduct various experiments towards the general public, all for their goal of creating a being that can rival All Might in power. Just like with the Underground Masquerade, he primarily made use of the Trigger drug, using Number 6 and the parasitic Queen Bee, Kuin Hachisuka, to expose it to the public and examine their out of control Quirks, turning them into Instant Villains.

Those who most fascinated them would be kidnapped and forced into bioengineering experimentations and body modifications, transforming them into Next-Level Villains, as just another step to test their Quirk potentials.

All the while as these events occurred, All For One kept a close watch over Number 6, under the guise of a mental illusion of his "Master O'Clock", providing him various advice. He observed Number 6's attempts to become the Pro Hero O'Clock II, and his Operation Anonymous revenge scheme when his plan fails. Recognizing how increasingly unhinged Number 6 gets, All For One is nonetheless intrigued over his development and wants to see where it will end up.

He continued to groom Tomura as his successor, well aware that Tomura was really the grandson of Nana Shimura and wanted to use this to his advantage. He also assigned Kurogiri with serving and overseeing Tomura’s development, warning Kurogiri to use Gigantomachia once he believes to no longer be capable of ensuring Tomura's safety. Sometime prior to the start of the school year, he created the League of Villains, an organization for Tomura to run and enlist villains to aide in his cause, while acting as a front for his true goals.

U.S.J. Arc
After failing in their attempt to assassinate All Might, Kurogiri warps himself and an injured Tomura back to their hideout at the last second, allowing them to escape from being defeated. Tomura berates over his failure, his injuries, losing all their subordinates, his Nomu being defeated, and All Might surviving. However, All For One, speaking on the monitor, says that nothing went wrong and that he was simply over optimistic. Tomura mentions one kid in particular who kept getting in his way, and had a power similar to All Might's, which interests All For One.

He says that it is too late to mourn and that they should gather a new group hand picked for efficiency, saying that they should take all the time they need. All For One tells Tomura that he's a symbol of importance and that next time he will show the world the horror of his existence.

U.A. Sports Festival Arc
A recuperating Tomura watches the U.A. Sports Festival, including the Obstacle Race where he sees Izuku take first place. Later on, before the battle between Izuku and Shoto Todoroki begins, All For One tells Tomura to pay close attention to their match as they might become obstacles for him in the future. Tomura responds by telling his Sensei to not make him laugh.

Vs. Hero Killer Arc
All For One, using his monitor to speak through, orders Kurogiri to allow Stain and Tomura to continue talking, saying that Tomura's meeting with Stain, an experienced infamous villain, will stimulate Tomura's growth. Before he leaves for Hosu, Tomura asks All For One to let him borrow some Nomu because he does not like the "Hero Killer" Stain and that destroying things he does not like seems alright. All For One decides to give Tomura three Nomu, hoping that Tomura will make the opportunity a learning experience.

In the aftermath of the incident, two of the Nomu are killed, one is detained, and Stain is captured. The latter surprises All For One, but he is still happy that things are going as he has foreseen. He exclaims that Tomura's position is to supervise and unify the new villains who have come to join the League of Villains. Doctor Garaki expresses doubt that Tomura can do his job and says that if All For One stepped in things would be proceeding faster. All For One proceeds to ask the Doctor to patch him up faster, adding that he will let Tomura do all the hard work so that he may become his successor as Tomura was born to do so. All For One tells All Might to rejoice in the "transient" peace while he still can.

My Hero Academia: Two Heroes
Learning about David Shield's plan to break into I-Island during its Expo, All For One contacted Wolfram, the Villain hired to assist in the scheme, and provided him with an additional Muscle Augmentation Quirk, wanting to have a hand in All Might's former partner's fall to villainy.

Hideout Raid Arc
After the Vanguard Action Squad's successful capture of Katsuki Bakugo and Ragdoll, All For One promptly stole her Search Quirk. He then had Doctor Garaki once again replicate his Quirk, believing he may be defeated soon, receiving a copy of the All For One Quirk for himself, while the original was kept by the Doctor, with the intention of passing down to Tomura when he's ready.

After Katsuki attacks Tomura in defiance of joining their cause, Tomura understands that mere words alone won't convince Katsuki to join them and decides to ask for the "force" of his teacher to help him convince Katsuki. All For One, who has been watching Tomura on his computer, commends his apprentice for his wise decision.

The League of Villains is soon apprehended by the Pro Heroes and Police Force. All For One decides to take action himself, emerging at the Nomu manufacturing warehouse, and apologizes to Tiger, explaining that Ragdoll is in a comatose state because he stole her Quirk, Search, which he found to be quite useful. Best Jeanist restrains All For One with his Quirk and orders his fellow Pro Heroes to not let the villain do anything.

Before the Pros can act, the entire warehouse is completely destroyed and the surrounding area suffers extensive damage as well. All For One had unleashed a blast wave that had seemingly killed the Pro Heroes, destroyed the warehouse, and dealt significant damage to the surrounding area in less than a second. All For One is livid with the Heroes for interfering with his apprentice, who has started thinking for himself as well as leading others by himself and hopes they no longer bother him. All For One decides to quickly resolve the mess created by the Heroes.

All For One uses a Warping Quirk to produce a black liquid at the League of Villains' hideout; the black liquid summons dozens of Nomu inside and outside the hideout, forcing the Pro Heroes and Police Force to confront the legions of Nomu. This black liquid also teleports the League of Villains and Katsuki away.

All For One discovers the Pro Heroes have survived his attack. All For One claps and praises Best Jeanist for using his Quirk to pull his fellow Heroes out of the way in order to reduce the blast's impact on them. Despite his heavy injuries, Best Jeanist attempts to fight back and begins sending fiber strings. However, All For One impales Best Jeanist from afar. The mighty villain mentions that he does not need his Quirk because it does not suit Tomura’s personality.

Tomura, Kurogiri, the Vanguard Action Squad, and Katsuki all materialize from the black liquid in front of All For One. The villain sees that his apprentice has failed again, however, All For One is neither angry nor disappointed with Tomura and encourages him to try again since he still has the Vanguard Action Squad and Katsuki whom he deemed important. All For One implores Tomura to continue trying as many times as he likes since everything is for his sake.

Suddenly, All Might appears above him and attacks him. However, All For One blocks his attack, as All Might declares that he will take everything back while All For One wonders if All Might will attempt to kill him again.

All Might and All For One clash, which creates a shockwave that sends Katsuki, Tomura, and the Vanguard Action Squad backwards. Both All For One and All Might criticize each other for becoming weaker. All Might declares that he will save Katsuki and will not repeat the same mistake as he did six years ago and this time he will definitely put All For One behind bars along with the League of Villains. All Might charges at his arch nemesis, but All For One sends another huge blast wave at All Might, causing the Symbol of Peace to be sent flying away with great force. All For One's blast wave attack not only hits All Might but destroys several buildings in the process.

Katsuki becomes concerned, but All For One tells Katsuki not to fret since his blast wave attack is not strong enough to kill All Might. All For One orders Tomura to escape along with Katsuki and comments that his black liquid warping Quirk will not be able to help Tomura and the League of Villains escape. All For One uses a Quirk that forcefully activates Kurogiri's Warp Gate, which causes a portal to open. All For One orders the League of Villains to escape into Kurogiri's portal. Suddenly, All Might reappears onto the battlefield, refusing to allow the arch villain to escape and charges at him. Before heading into battle, All For One tells Tomura that he can still grow stronger.

All Might and All For One clash once again, while Katsuki tries to fend off some of the Vanguard Action Squad trying to apprehend him; All Might attempts to help Katsuki only for All For One to intervene and stop him. Suddenly, Izuku, Eijiro Kirishima, and Tenya Ida appear above them in the air; All For One sees the trio and attempts to attack them, but All Might intervenes by punching him.

Katsuki manages to use this opportunity to escape along with Izuku and his friends. Now that the tables have turned, All For One sees that they no longer can secure victory due to Katsuki's rescue and that most of the Vanguard Action Squad is unconscious. All For One decides to save Tomura and the Vanguard Action Squad, forcefully activating Magne's Magnetism Quirk. Before Tomura can stop, he and the Vanguard Action Squad are magnetically pulled into Kurogiri's Warp Gate. As he is being sucked into the Warp Gate, Tomura calls out to his teacher concerned for his safety. Before Tomura teleports away, All For One tells Tomura to continue the fight. Tomura and the unconscious Kurogiri are teleported away by the Warp Gate, causing the portal to disperse.

All Might charges at All For One, but All For One uses his Warping Quirk to teleport Gran Torino in front of him, using the elderly Hero as a human shield which causes Gran Torino to take All Might's attack instead. All For One expresses his hatred for All Might as he is the one who brought down his comrades in the past and while he descended into darkness, All Might rose to the top as the Symbol of Peace. All For One prepares to fire his blast wave move, intending to blow away Gran Torino and All Might at the same time. However, All Might pulls Gran Torino away and uses a Detroit Smash to cancel out All For One's blast wave move.

All For One sees that his destruction of the city has brought chaos and decides to put the innocent civilians in danger so that All Might will not be able to fight at full strength. Furious with All For One's sadism, All Might grabs his arm while throwing Gran Torino away for safety. All Might admonishes All For One for all the despicable crimes he has committed and for his misanthropy.

All Might punches All For One in the face, shattering his mask; however, All Might's punch was not strong enough to finish him off. As Gran Torino calls out to him, All Might's face reverts to its true form. All For One says that All Might would not be the first to criticize him as he has heard those same lines before, from the previous One For All successor: Nana Shimura.

All Might is angry at the arch villain for mentioning her name, as All For One notes that Nana was all bark and no bite, only going on about her ideals, and was not even strong; he mocks her for her uselessness and mentions that she died in an embarrassing, shameful way. Furious, All Might prepares to attack All For One, but he proceeds to use his blast wave technique against All Might, causing the hero to be blasted into the air. Gran Torino catches All Might and lands him to safety on the ground.

All For One decides to finish his apprentice's hard work and sever the trust in heroes once and for all. He once again expresses his hatred for All Might due to taking something away from him and wants him to die in the most gruesome way possible. He fires another wave blast attack at All Might, who, seeing that an innocent civilian is trapped under rubble behind him, blocks All For One's attack and saves the civilian from being harmed. However, All Might expends the last of his power and reverts to his true form. All For One relishes in the fact that All Might's true form has been exposed for all to see.

Everyone around the country sees All Might's true form and begins panicking. All For One mocks All Might for the pitiful state he is in. However, All Might does not care about his rotting body nor his exposure to the world and declares that his spirit burns strongly which is what truly matters. Wanting to break his spirit even more, All For One reveals that Tomura is Nana's grandson. All Might is demoralized and refuses to believe, but All For One tells him that it is the truth. All For One wonders why All Might is not smiling and sarcastically remarks about All Might's smile, which is something Nana would always do. All Might's spirit is greatly demoralized by the mockery while All For One continues relishing in All Might's pitiful state.

Invigorated by the civilian, All Might activates One For All throughout the right side of his body, transforming it into its hero form. All Might smiles and states that Heroes have many things to protect which is why they do not lose.

All For One deduces that All Might will unleash his final attack, commenting that wounded Heroes are the most terrifying of all. All For One's comment causes him to reminisce about their last battle where All Might delivered the final blow to him and admits that the look on All Might's face during that last attack has still haunted him to this very day. All For One prepares to fire his blast wave attack, when suddenly, flames strike at the mighty villain, which All For One uses another wave blast attack to swat away the flames with ease. All For One is surprised by the appearance of Endeavor and Edgeshot, specifically how they were able to make haste of the Nomu much faster than he anticipated, and that he shouldn't have taken Endeavor's No. 2 rank so lightly.

Annoyed with the Pro Heroes' interference, All For One prepares his blast wave attack again. However, Edgeshot uses his Quirk and great speed to attack, but All For One dodges the attack. Growing tired with the sentimental talk, All For One blasts Endeavor and Edgeshot back and activates a number of his strongest Quirks in his right arm, causing it to become an enlarged mutated arm filled with numerous deadly screws and hardened minerals.

All For One charges at All Might with his heavily empowered and mutated arm. While heading towards All Might, All For One knows from battling him that All Might no longer has One For All, and that he is simply fighting with the remaining embers that have all been extinguished. He further tells All Might that he knows to whom he gave One For All to: Izuku Midoriya, having deduced it from Tomura's report about the boy. All For One taunts All Might by saying that he has also failed as a teacher towards Izuku due to his apprentice's recklessness.

Both All For One and All Might clash by punching each other with their enhanced fists, which creates a huge shockwave that devastates a great portion of the city. As they struggle, All For One uses his Impact Recoil Quirk to revert all the damage to All Might. However, All Might transfers One For All to his other arm, sacrificing his right arm but renders Impact Recoil ineffective. All Might says that he must indeed criticize Izuku for his actions, while All For One is shocked that All Might would go to such lengths to protect his leftovers of One For All and admits that he miscalculated. All Might refuses to die until he has finished bringing up Izuku, and then counters by throwing his empowered left arm and punches All For One who has left his guard open.

The punch, however, was meant to lower All For One's guard, and All Might transfers One For All to his right arm and prepares for his final attack, United States of Smash, which creates a great shock wave when it hits All For One. After the dust clears, All For One is in a crater, badly beaten and unconscious. Later, Endeavor and All Might watch All For One being placed in the iron maiden.

The next day, All For One is incarcerated into Tartarus, a special prison for criminals for whom the death penalty is not enough. All For One, in a wheelchair and on life support, wonders where he is, much to the prison guard's annoyance who is pushing him to his holding cell; the prison guard tells him his location. All For One apologizes, causing the prison guard to assume that he is unable to see. All For One reveals that for the past six years he has been using an Infrared Quirk to sense his surroundings as a way to compensate his blindness, but due to all the sensors he is unable to sense anything and apologizes to the prison guard. The prison guard is flabbergasted that All For One fought All Might in such a condition.

While being pushed to his holding cell, All For One is not angry or upset for losing against All Might. Instead, All For One is happy because his defeat at All Might's hands will grow Tomura's hatred for All Might as well as his regret for being unable to save his Sensei, which will motivate him to gain experience and become much stronger. All For One smiles, knowing that even though he lost the battle, he still will succeed at being the better teacher than All Might, and that his successor will come out on top.

Provisional Hero License Exam Arc
During the Provisional Hero License Exam, All for One receives a visit from All Might. All For One comments on the severe strictness of the prison he is being held in, that even if he were to try and activate a Quirk, he'd be put down instantly. All Might assures All For One that he will never escape nor is he getting out anytime soon from this prison of hell.

Moving along, All For One questions again what All Might wants. The former hero wants to know the whereabouts of Tomura, which the villain answers that he doesn't know and unlike him he has already let Tomura carry on. All Might proceeds to question him about his motives, but the villain claims All Might is never going to be satisfied by his answers. All For One makes his answer simple; both he and All Might are the same. All For One wishes to be the king of evil in the same way All Might wants to be the symbol of peace.

All Might asks if All For One wanted to live forever being utterly evil, then why does he need a successor. All For One finds All Might's question funny, answering that All Might took everything away from him, leaving him in a regrettable state to the point he needs complex devices to survive. Because of this, his influence and ideals had become limited thanks to him, so he has been grooming Tomura to become his successor and carry on his legacy.

The security inform All Might that he has three minutes left, much to All For One's disappointment as he still has much more to say. Due to All Might's retirement, the villain asks about the state of the outside world, but the security inform All Might that he cannot tell him any information that is going on in the world. All For One decides to make a hypothesis then: with All Might's retirement, Endeavor has become the new number one Hero, however, it does not seem that it will be enough to contain the anxiety and concern of society, and sensing the growing insecurity in the world, the villains will rise up, believing it to be their chance to change society.

In this situation, Tomura and his allies will grow in power and influence to reach the top, although they will have to clash other organizations that also intend to do the same, clashes in which All Might will be unable to do anything. All For One mockingly asks All Might how it feels to be absolutely powerless.

His words make All Might angry, who replies to All For One not to presume everything. All Might understands that he chose Tomura as his successor because he was the grandson of his master Nana, but he will not allow All For One's twisted vision to be realized and he won't let himself be killed by Tomura. All For One wonders if All Might came here to tell him that. As he leaves, All Might tells All For One he will smash his plans as many times as it takes, and he will pass the rest of his life in prison. As the prison cell begins closing, All For One chuckles at All Might's final statement.

Pro Hero Arc
All For One claims he is willing to restore Ragdoll's Quirk back to her but that it would require activating his own Quirk to do so. The authorities determined the safest approach is to not let him do anything while investigating the number of Quirks he has stockpiled.

A few days later, Izuku experiences the vestiges of One For All where he views a flashback between All For One and Yoichi, the first user of One For All. He witnesses All For One transfer the stockpiling Quirk on his brother, out of kindness as well as to force him to submit. All For One claims that he was creating a reality just like the one in the comics the brothers used to read as kids. He also tells his brother that by acquiring a Quirk he would start seeing the reality as it is.

Joint Training Arc
In Tartarus, one of the prison guards grows anxious regarding All For One's presence, wondering when his sentence will be finalized, with the other stating that it's been delayed due to unknown factors like Gigantomachia and the League still being at large, and not wanting to make All For One into a martyr for the villains.

All For One suddenly starts to speak, shocking the guards, and apologizes for setting off the alarms due to feeling uneasy due to having started to reminisce about things from his past, claiming to hear his younger brother's voice.

Paranormal Liberation War Arc
While investigating and analyzing Kurogiri, who they had captured several months ago, Naomasa Tsukauchi and Gran Torino find out that he is a Nomu created from the corpse of Oboro Shirakumo. When they question All For One about his methods to create the Nomu, the villain simply responds with a metaphor in which he compares the creation of the Nomu as producing wine: trampling grapes (people) to extract the juice (Quirks), and letting them ferment into wine (Nomu).

Later, Naomasa and Gran Torino ask Shota Aizawa and Hizashi Yamada for help to awaken Oboro's consciousness. Although it was an emotionally painful process, they succeed and obtain vital information. This, along with other data obtained by Hawks, allows the Heroes to locate Tomura, who is at the Jaku General Hospital, undergoing a complex and extensive operation at the hands of Kyudai Garaki to obtain more power, transplanting the original All For One Quirk to him.

To avoid this, the Heroes raid the hospital a month before the operation ends, as well as other bases of the Paranormal Liberation Front, a formation between the League of Villains and the Meta Liberation Army. Not without great difficulties, the Heroes manage to reach the secret laboratory under the hospital and prevent Kyudai from awakening Tomura prematurely, destroying the machine that kept them alive, with even Kyudai believing that his master's dream has ended due to Tomura appearing to be dead.

While Tomura is in this state of apparent death, he enters a dreamworld where he sees and interacts with representations of his relatives, until a shadowy vestige of All For One appears, telling him to come to him. Tomura's family reappears to stop him, even his grandmother Nana, yet despite their pleas to not fall into his darkness, Tomura rejects them and embraces his master.

Tomura unexpectedly awakens, and immediately uses his empowered Decay to destroy the hospital, killing dozens of heroes in the process, and even destroying much of the nearby city. After this, he orders Gigantomachia to come to him, bringing the members of the League with him, but he also begins to hear a voice inside his head that orders him to go get the One For All Quirk. Tomura begins to be attacked by Endeavor and other heroes, but impelled by the voice inside him, he uses his Search Quirk to locate One For All, discovering it in possession of Izuku, heading towards him.

Tomura manages to reach Izuku, starting a bloody battle between him against Izuku, Katsuki, Endeavor, Shota Aizawa, Gran Torino, and several other heroes. To prevent more heroes from interfering, Tomura summons a group of Nomu to confront the reinforcements. While all this is happening, All For One is seen smiling within his cell.

While facing Izuku, Tomura ends up calling him his "little brother"; a statement that leaves both of them confused. This allows Tomura to realize that the mysterious inner voice comes from the ego of his master that exists within All For One, who tries to take over his will. Tomura thanks his master from for raising him from the bottom of his heart, but refuses to controlled by him, as he wants to be greater than All For One was, and breaks free from his image in his mind.

After Tomura gets severely injured by Endeavor's Prominence Burn attack, All For One reaches out his hand and suggests Tomura hand his body over to him. He appears to do so as suddenly a completely entombed Tomura attacks both Endeavor and Izuku with the tendrils of his Rivet Stab Quirk. Endeavor gets impaled, but Katsuki pushes Izuku out of the way, and gets impaled instead.

Tomura attempts to wrestle back control over his body, while All For One comments that of all the blood shed on the battle, Katsuki's was the most pointless. This causes Izuku to snap and try to attack Tomura directly, as he notices All For One starting to emerge from within Tomura. With him distracted, Tomura manages to grab ahold of Izuku and uses All For One to try and steal One For All. Instead, Izuku ends up within a vestige world where he sees All For One fused with Tomura, where Tomura demands All For One not to interfere, but All For One sneers that if it weren't for his intervention, Tomura would be dead.

Suddenly, Nana appears alongside Izuku, as All For One exclaims to Tomura how his dead grandmother has joined them. He goes on to tell them how when he stole Quirks, he could hear voices, which caused him to feel some semblance of guilt. However, once he relinquished the Quirk, the voices would go away. It wasn't until he met Dr. Garaki that he realized it was the vestiges of the previous owners he had heard, similar to how organs and cells contain a person's DNA. All For One admits he thought he was the only person that could do this and realizes when his Quirk merged with his younger brother's, it granted him and anyone else who had One For All the ability as well.

One For All starts to crumble, as All For One gleefully states that Tomura's rage is overwhelming One For All's will, noticing that this also includes Tomura's hatred for All For One himself, which he is pleased for as it makes him worthy of being the Symbol of Chaos. Just then, Yoichi appears and helps Nana to push back Tomura's anger. He asks his brother if Tomura is just the next person he is manipulating, while All For One says he wishes he had made his brother his, but that Yoichi refuses to join him.

All For One forces Tomura to combine their powers together to take One For All, stating that Izuku is unworthy since he couldn't protect his friends or teacher. Yoichi says they deem Izuku worthy and All For One will never understand why as he and Nana counter All For One and Tomura, causing Izuku and Tomura to separate and regain consciousness.

All For One tells Tomura that they failed and they must retreat and let his body reach 100%, but Tomura refuses and decides to stay and fight against All For One's insistence. All For One takes note of Gigantomachia's arrival and states that he came just in the nick of time, before Tomura falls unconscious.

Spinner, who is tending to Tomura, remembers what his leader had said before about the hands of his deceased family bringing him a sickening rage and puts one of those hands onto Tomura's face. This allows Tomura to reawaken, though All For One is now in full control. He remarks on how his successor found himself some truly great allies, and that the hatred in Tomura's heart serves as a power that gives the vestige of All For One an even greater hold over Tomura's body.

All For One uses his Radio Waves to order the Near High-End Nomu to take Tomura's body and retreat. When Spinner reminds All For One of their allies still fighting, the villain coldly states that since Tomura lost, it is only fair that he pays for that loss and subsequently abandons the remaining members. Just before they leave, Izuku attempts to stop All For One, but the villain easily blasts him away with an Air Cannon and tells the hero that they will meet again once Tomura's body is perfected.

The vestige of All For One retreats with the remaining ten Near High-End Nomu, accompanied by Spinner and a compressed Dabi and Skeptic. The surviving heroes try to stop them, but All For One dispatches three of the Nomus to confront them. The Near High-End’s distraction tactics ensured that he, his allies, and seven others escaped while those three were destroyed.

A few hours later, in Tartarus, the real All For One is able to sense the condition of Tomura's body, noting that while his expectations were slightly off, it wouldn't be much longer. In the forest, the vestige of All For One remarks that the heroes won't get a tomorrow or the chance to get a moment's rest, since it is his turn to lead, ordering the Near High-Ends to invade Tartarus to free his real body.

All For One in Tomura's body alongside the Near High-Ends start to invade Tartarus. They destroy the Bronze Gate, as the bridge is lowered halting them from entering. The Near High-Ends deal with the defending drones, while All For One flies over on a flying Nomu. Tomura starts to wake up, leading to an argument between the two over control of the body. All For One reminds him he's doing everything for his sake, because Tomura will become "the next me". As All For One struggles to break through, due to the immense amount of security in Tartarus and Tomura's increasingly-failing body, he figures the only way to success is through a coordinated attack inside and out, and that he'll need help from villains.

All For One proceeds to hit Tartarus with several Radio Waves attacks from outside in Tomura's body, shutting down the prison's security, followed immediately by another Radio Waves attack on the inside by himself in his original body, unlocking his and all the other cells on the floor, as the previously captured villains quickly disposed of the armed guards. The vestige and original All For One use Radio Waves to communicate with each other, telling each other their intention to have Tomura's procedure completed within 38 days. The freed (albeit still on life support) All For One then finally reunites with Tomura, in front of the rest of the prisoners, telling them to join him on his path of devastation, to become the greatest demon lord.

To majority of the inmates, All For One tells them to be free and cause as much chaos as they want. He then approaches Lady Nagant, telling her it was an honor to meet the "treacherous hero", while she reminisces how he was one of her targets back in the day. He requests her to hunt down a specific target: Izuku Midoriya, sure that he will leave U.A. and asks her to capture and bring him to him. He also warns her that surely some of the best heroes will be watching over him from a distance, so he recommends her to take her time until they are split up enough, with waiting for a rainy day being her best bet.

Lady Nagant interrupts him by asking why she is the only one with an assignment while the other inmates can just go wild. All For One reminds her how she killed a fellow Hero and that she wants the Hero Society to collapse as well, and as long as Izuku remains, that dream will never come to pass.

All For One notices the mentally broken Kai Chisaki muttering about his boss, and asks if he's a friend of hers. She denies this, but she brings him with her because she believes he will be useful to her in some way despite his mental state, as All For One identifies him as another victim of the 'wicked' Hero Society. Nevertheless, Lady Nagant agrees to help All For One and to seal their deal, he offers a gift, and transfers Air Walk to her. After telling her to deliver the target within two months to a mansion in Haibori Woods, he proceeds to give the same task to several other dangerous criminals as well.

After escaping from Tartarus, All For One orchestrates another large-scale attack, using both the Nomu and the freed prisoners to attack six different prisons all to distract the authorities and make it harder for them to track him. All For One is later seen sitting with "Tomura" and asks Spinner and Dabi to stand guard over him while his body recovers. Spinner asks who Tomura really was, stating All For One wasn't the person he chose to follow. All For One tells Spinner not to worry, saying he has the greatest respect for Tomura's will and that once his body recovers, both of their desires would come to fruition.

Tartarus Escapees Arc
One month later, Lady Nagant tracks down Izuku and begins to capture him to execute All For One's orders. In the subsequent duel, Izuku defeats Lady Nagant and requests her to join his cause, only to suddenly have her explode.

As it turns out, All For One had been monitoring the battle from an unknown location, and anticipating Lady Nagant's possible failure, had secretly transferred a self-destruct Quirk, which he had detonated upon sensing her change of heart. He mocks Lady Nagant for being a woeful and pitiful woman, remarking that she was nothing but a tool to achieve ends from everyone, and she should blame her Quirk for her tragedy.

Expecting Lady Nagant to also reveal the location of their proposed meet up, All For One sets up a trap in the former Creature Rejection Clan hideout, leaving behind a pre-recorded message for Izuku to find. In the message, he taunts Izuku for knowing that someone like him couldn't abandon someone like Lady Nagant, adding in that he didn't force her to join him and that it was her choice. He continues on about how those in society who fall are labeled as "villains", and even if one takes pride in their Quirk, if you can't fit into the controlled society, you'll be excluded, citing it as human nature. He concludes stating the more Izuku fights the more his soul will wear down, and reveals that while in prison, he was the one he never stopped thinking about, no longer having any interest in All Might, telling him it's "his turn" as the mansion explodes.