Kyudai Garaki/Synopsis

History
Kyudai was born approximately 120 years ago, manifesting a Quirk that granted him great longevity, Life Force, although he made everyone believe that he is Quirkless. Over time he became a doctor and scientist dedicated to the study and research of the Quirks.

About seventy years ago, Kyudai theorized the "Quirk Singularity", according to which as the generations pass, the Quirks will become so powerful that they will be uncontrollable. However, his theory was lauded by society, who viewed the concept as ridiculous and didn't want to listen to a far-fetched doomsday theory when society was still struggling with assimilating quirks into society. As a result, Kyudai was ostracized and disappeared from the public eye.

Left alone and with nowhere to go, he was approached by All For One, who believed his theory and lended Kyudai his aid. It was then that Kyudai began working with 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.

Sometime later, All For One found a discarded boy named Tenko on the streets, after having gone through the traumatic event of killing his family when his Quirk Decay manifested for the first time. At his master's request, he brought for several sets of hands belonging to the boy's family who were accidentally slaughtered when the boy's Quirk manifested. Kyudai watched as the boy started experiencing episodes from recalling the events. Kyudai questioned All For One if he should modify Tenko, but All For One declined and stated that he will teach him how to take his feelings and frustrations and give them purpose.

He eventually became All For One's personal doctor after he was defeated by All Might, being critically injured.

At some point, Kyudai interviewed Nine as a candidate for an experiment, which is research for the All For One Quirk. Kyudai points out that despite having a powerfull Quirk that results in the destruction of cell tissues, Nine has managed to live out a normal life, without anyone noticing anything peculiar about him. Kyudai then questions Nine's motives, to which he bluntly refuses to explain at first. However, Kyudai points out that keeping secrets will only disqualify Nine from the experiment, forcing the latter to open up about his past.

After listening to Nine's explanation of his past, Quirk, and ideology, Kyudai concludes that Nine is the perfect candidate, as his body and mind are in the right condition. Kyudai would then put Nine in an unknown machine, undergoing the experimentation process Kyudai planned out for him.

U.S.J. Arc
While Tomura was reporting of his mission's failure of killing All Might, Kyudai expresses annoyance at his Nomu being defeated before All For One calms him since they've found something intriguing about All Might's students.

Vs. Hero Killer Arc
All For One is surprised that the Hero Killer Stain was captured but 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. Kyudai 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 asks him to patch him up faster. All For One says that he will let Tomura do all the hard work so that he may become his successor as Tomura was born to do so.

Pro Hero Arc
After Endeavor and Hawks' fight with the Nomus, High-End, Dabi confronts the two heroes and initiates a fight with them. He is interrupted by Mirko, prompting Dabi to retreat by asking Kyudai for help. Kyudai has Dabi warped away.

Meta Liberation Army Arc
A month prior to the Hero Billboard Chart JP event, the League of Villains were facing Gigantomachia. As they were struggling against the behemoth, Kyudai contacts them from the radio that Gigantomachia is wearing, as he implies Tomura's uncertainty in the League's current state and need for help. Tomura was shocked to hear his voice.

Kyudai asks Tomura Shigaraki if he's keeping his remaining allies healthy, in which the latter admits that the League is running short on members. However, A sad tearful Gigantomachia proceeds to destroy a majority of the landscape, Kyudai introduces more info on Gigantomachia to the League, explaining that he once served as All For One's bodyguard. The doctor points out that the colossal beast possesses unlimited stamina and capable of welding multiple Quirks without any complex modifications. The doctor adds on that as All For One's power began to wither away thanks to All Might, the megalomaniac knew that he'll eventually meet his defeat, thus leading to him hiding Gigantomachia from the public eye.

Before Gigantomachia prepares to unleash another one of his devastating attacks, Kyudai plays a voice recording of All For One from the radio that effectively calms Gigantomachia as he cuddles up to the voice of his "beloved" master. An irritated Tomura claims that he doesn't want to handle Gigantomachia. The doctor tells the young pupil that he spent too much time with Kurogiri and tells him to grow up. Suddenly, black ooze emerges from the League's bodies, transporting them all to a secret laboratory filled with multiple Nomu hybrids.

It is revealed that the doctor was responsible behind the Warping Quirk once used by All For One from the Kamino Incident. He reveals that All For One did this just to make sure his legacy would live on through Tomura's command. The Doctor calls them High-End and says they're much more advanced than the old Nomu. Tomura asks if the Doctor if he can duplicate the Quirk-Destroying Bullets.

In Kyudai's lab, Mr. Compress says that he can't see the Doctor, and this spooks the latter into hiding in a dark tunnel. The Doctor apologizes and explains that they are not to approach him unless they want to be transported back to Gigantomachia. He introduces himself as Daruma Ujiko, an admitted alias. Kyudai tells Tomura that he's only helping out of loyalty to All For One. He claims Tomura himself hasn't accomplished anything and he that must prove that he can carry on All For One's will.

Kyudai listens when Tomura confesses that he felt empty before meeting All For One and that the hands he wears on his person make him feel both nauseous and at peace, yet his heart feels heavy which causes his rage. However, Tomura explains that it's this juxtaposition of feelings that makes him hate everything and want to destroy everything. Tomura tells Kyudai that he will show heaven and hell if he will help. Amused, Kyudai responds that it's a childish dream but is impressed by how serious Tomura is in his dream. Kyudai agrees nonetheless.

Mr. Compress notes how easy it was to convince the doctor. Kyudai admits that the plan was to always help but he wanted to see Tomura's development. He also admits that he cannot help until they get Gigantomachia to submit. Dabi interrupts saying he will not go back to fight Gigantomachia plus he has a good potential ally waiting. Kyudai interjects that Dabi can stay back to help him test the High-End Nomu Hood. Kyudai sends the remaining League of Villains members back to Gigantomachia at Tomura's request using Johnny.

During the following month and a half, Tomura and the rest of the League members fight almost constantly against Gigantomachia, having only a few hours of rest between combats. Keeping his word, Kyudai refuses to fully help the League until Gigantomachia submits. He only gives them a one-time meager allowance. During one of these breaks, they receive the call from Re-Destro, Grand Commander of the Meta Liberation Army. Re-Destro explains that the Army desires to destroy the status quo and allow people to use their Quirks freely, but the League's popularity is interfering with their plans, so they have kidnapped Giran. He explains that only the Army can be credited with the revolution that changes society, therefore the League of Villains must be eliminated to signal the Army revival. Re-Destro informs Tomura to go to Deika City in Aichi Prefecture within the next hour if he wants to get Giran back. He ends the conversation, giving Tomura two choices: 1.) stand against the Army and be destroyed or 2.) do nothing and be captured by the heroes when he gives their location.

Tomura decides to accept the challenge, saying he has a plan. He radios the doctor, who is surprise that the Liberation Army still exists. Mr. Compress thinks that Tomura is going to ask Kyudai to send a High-End Nomu, but the doctor clarifies that is not possible because they are not ready for testing and he cannot do much in regards to producing more Nomu without All For One's help. Tomura comments he did not want to rely on the Nomu, his plan is to kill two birds with one stone: use Gigantomachia against the Army. Once the Meta Liberation Army is decimated by Gigantomachia's rampage, he plans to attack Gigantomachia, hoping the Army weakened him enough to finally take him down.

The doctor yells how underhanded Tomura is being and wonders if Re-Destro was bluffing. Tomura replies, "Then the fool dies. Plain and simple." at the doctor's thought. They still have over two hours until Machia wakes up, and Tomura asks the Doctor to warp the entire League of Villains to Aichi. Once in Deika city, they are attacked by members of the Liberation Army.

Later on, members of the League endure almost an hour of battling the Meta Liberation Army and cause a large number of casualties to the opposing side, but members of the League begin to show weariness by the consistent battles and increasingly powerful enemies. Overhearing everything from his lab, Kyudai decides to help by waking Gigantomachia prematurely and ordering him to the League's location. Doing so causes, Gigantomachia to erupt from under a wooden mound.

When Gigantomachia was heading for Tomura Mr. Compress was calling to warp them out, but Kyudai declined, saying that the League first needs to get the Liberation Army to stop tracking them. Compress then states that Tomura might get killed and asks if that's what All For One would've wanted, but the doctor replies saying that because Tomura is his master's successor, he needs to get pushed into the corner.

After the fight with the Meta Liberation Army and the merge with the League of Villains, Tomura contacts the doctor. Kyudai is pleased with the progress such as Tomura regaining his memories, taming Gigantomachia, and comments on the reinforcement of the Paranormal Liberation Front and asks Tomura to do a little favor.

Endeavor Agency Arc
While the Paranormal Liberation Front prepares for when the time comes to attack, Kyudai prepares to perform an operation in Shigaraki to grant him even more power. Given that he is already very powerful, Kyudai asks Shigaraki why he wants even more power. Shigaraki gives you two reasons: first, because he had promised him more power if he met his requirements. And secondly, because he wants to use everything he has at his disposal to obliterate the drags All Might left behind.

Kyudai likes Tomura's proclamations and explains the situation. Thanks to the operation he will perform on it, he will obtain suitable body to control a power much greater than that of All For One, to the point he can even obtain the One For All. However, Kyudai also assures Shigaraki that the medical process will last four months, and he will endure four months of hellish agony.

With the situation clarified, Kyudai begins to operate in Tomura.

Paranormal Liberation War Arc
A month has already passed, and Dr. Kyudai is excited at how well his operation on Tomura Shigaraki is going; in fact, it seems to be going even better than he planned. Kyudai is impressed with Tomura and cheering him on from the sidelines while contemplating how, in the operating room, Tomura goes through a painful and gruesome process to obtain more power.

In late March, on the day that heroes vanished from the city, Dr. Kyudai is seen walking through a hospital. He greets a nearby nurse, who remarks that it's a rare sight to see him. Kyudai is in a pleasant mood, whistling while he thinks about the progress Tomura has made. He remarks that Tomura will be complete in under a month and that he can't wait. However, he's interrupted by Endeavor, who knows the truth about Kyudai and his relationship with All for One, causing the doctor to scream in terror.

Kyudai attempts to flee, but Eraser Head grabs him with his capture weapon, then uses his Erasure Quirk on him. Kyudai rapidly begins to age, revealing that he is not Quirkless, but has a longevity quirk similar to All for One. Naomasa deduces that Kyudai managed to artificially create quirks, replicating the rare regeneration quirk for the Nomus and offering his power to All for One. Present Mic grabs Kyudai by the collar and demands to know why he's using his power for evil. Kyudai demands the heroes to let him go, smiling as he waits for reinforcements to arrive.

Suddenly, several Nomu burst out of the floor. Kyudai's body begins to melt, and he reveals that he's a clone made by Twice. The real Kyudai is still in his workshop, preoccupied with his "masterpiece". Even so, he begins to panic at the fact the heroes discovered his laboratory underneath the hospital, revealing the countless number of quirks he's replicated throughout the years as well as the High-End Nomu he's still developing. He laments the choice but ultimately orders Johnny to warp him and Shigaraki far from there. However, the hero Mirko bursts into the laboratory, killing Johnny before he can warp them and causing the doctor to scream in terror once again.

Kyudai watches on in horror as his laboratory starts crumbling apart thanks to Mirko sending multiple pieces of metal flying straight at his multiple test tubes and replicated Quirk jars. This also destroy some of his High-End Nomus in the process. Mirko attempts to subdue the Doctor but the latter tells the Pro Hero that he is indeed the real deal. However, one of his Nomu "Mocha" intervenes by using Twice's Quirk. Mirko manages to destroy Mocha before it does any harm and scrapes a bit of Kyudai's clothing. Having no choice but to flee, Kyudai reluctantly activates the remaining five High-Ends to hold off Mirko as he retreats to his workshop to awake Tomura prematurely.

While Mirko fights fiercely against several of the High-Ends, Garaki works on his computer, complaining about how producing just one of those creatures is hard process, especially without All For One. He also says that the High-Ends barely had any sort of trial run, but with Mocha and Johnny dead, Kyudai mentally pleads them to hang on for as long as they can while he begins the process to wake Tomura up. After spending several minutes fighting against the High-End, despite having managed to eliminate one of them, Mirko understands that she starts to lose the upper hand, so he decides to prioritize stopping Kyudai instead of continuing to fight. To the doctor horror, she manages to catch up to him and Tomura in his capsule. One of the High-End gets caught her by stabbing through her right leg with its Quirk, but at that moment heroes like Endeavor, Eraser Head, Present Mic, Crust and several more stormed the laboratory and attack the High-Ends, giving Mirko the opportunity to uses her Super Move Luna Arc to damage Tomura's life support, before being dragged away by the Nomu.

Panic is reflected on the doctor's face when he sees the destruction caused by Mirko's attack, but still, the damage is not enough to stop the process, so Mirko desperately yells her allies to destroy the capsule containing Tomura and take down Kyudai, whose name is heard by an irate Eraser Head and Present Mic, as they can't let Tomura awaken no matter what. As much as he didn't want to wake Tomura because he is still in an incomplete state, Kyudai figured it would be better than before all the solution inside the capsule is lost. As he laments how all his work with All For One was falling apart, he pulls out a switch and tries to press it while yelling for Tomura to wake up. Before he can though, Present Mic appears and uses his Voice Quirk to shatter the capsule completely, leaving Kyudai aghast. Then Present Mic quickly runs up to him and delivers a DJ Punch right to his face to confirm he is not a clone, and in retaliation for what he did to Oboro Shirakumo and the emotional pain he caused to Shota Aizawa because of it.

The hero X-Less checks on Tomura and notes his heart is not beating. Crying out of despair, Kyudai reveals he put Tomura into a deathlike state to better withstand the stabilization. He proclaims lived for Shigaraki's sake but he failed. With more and more heroes storming his lab and defeating his Nomus, Endeavor proclaims that the Devil's Dream has finally ended.

Present Mic then drags Kyudai across the lab, demanding him to stop the Nomus. Kyudai tells him about society's rejection of his Quirk Singularity Theory and how everyone hated the idea of a collapse for the future, to the point where he was ostracized and exiled, until All For One accepted him. Kyudai reveals that the name of his longevity Quirk is Life Force and he gave it to All For One as an offering, while keeping a copy of it for himself.

Kyudai then rhetorically asks Present Mic if he is a friend of Kurogiri, confessing that back then when his friend Oboro died, he actually wanted to get his hand on Shota Aizawa's Erasure, leading Hizashi to resent him while he grins madly.Despite having previously verified that his heart was not beating, Tomura Shigaraki awakens,. Seeing the situation, he immediately uses his Decay, which spreads rapidly through the laboratory. Garaki and Hizashi notice the lab starting to disintegrate, with Kyudai smiling maniacally as it reached closer to the two of them. Gran Torino charges in and quickly grabs the two.

The laboratory begins to crumble, and the heroes try to flee as they can from the destruction. Most of them die because of the Decay, which destroys the entire hospital, spreading to the city. An ecstatic Kyudai declares everything the Heroes built will disintegrate at Tomura's hands, so this is their victory.

During the fight of Tomura and the Heroes, Kyudai Garaki reveals to Present Mic that the strength he gave Shigaraki isn't on par with All Might because excessive modifications to the body would take its toll on the brain, however it is close to it. Eraser Head wonders if this is what a perfected Nomu is supposed to be.

A flashback reveals Tomura's meeting with Kyudai and him asking if the Nomu will go out of control, but he said they won't. Kyudai explains that they will only move once an electric current flows through them, and all he needs is to tap the device given to him to wake them up, after which they are programmed to obey only his orders. In the present, Tomura considers the Nomu servants befitting a king.

The doctor praises Tomura for saving the High-Ends and they were activated when he used "Radio Waves". He does admit they haven't reached the testing phase so they can't think for themselves, but their strength is phenomenal, so he classifies them as 'Nearly High-Ends'. Mic takes Garaki to the nearest police force and is informed of the situation by a policeman: Gigantomachia goes to where Tomura is, destroying everything in his way. Hearing this, Kyudai begins to brag and Hizashi listens with concern as the doctor boasts that the heroes have lost the battle. He also tells the police and Present Mic that Gigantomachia is a calamity that lives and dies for the sake of his master; in fact, the Nomu were modeled after him.