Toshinori Yagi

Toshinori (俊典), more commonly known as All Might (オールマイト), is the No. 1 Hero. He also teaches foundational hero studies at Yuuei.

Appearance
In his hero form, Toshinori is a very tall and over-muscular man, whose design resembles the American hero comics. His hair spikes on top of his head and his whole body has more shadows than any other character in the series regardless of the time of day, furthering his stylized appearance. His hero costume consists of a red, white, and blue body suit with golden gloves and boots. It has been shown with and without a cape. Overall, its design is considered very classic.

In his true form, he is an overly-skinny man with angular features, long limbs and neck. He has spiky, disheveled hair with two bangs framing the sides of his face and loses his eyebrows from his hero form. He possesses a large scar that covers most of the left side of his chest, and it is not uncommon for him to spout blood from his mouth when excited or surprised. He typically wears baggy clothing to accommodate his Quirk's size change.

Note that in both forms, his eyes are sunken in, but the difference is that you can see his eyes in his true form.

Personality
Toshinori's hero persona derives much from American hero stereotypes, in which they are colorful and have a lot of dramatic flair. Always sporting a giant smile, he usually shows off a bright, can-do attitude that borders on being obnoxious. He also tends to be extremely friendly and amicable, due to his popularity and years in the spotlight. However, when he reverts back to being sick and scrawny (as a result of a previous battle), he tends to be less energetic due to his constant blood-spitting. Additionally, he tries not to draw much attention to himself while in his true form, always afraid that others might learn of his current state of health.

Two personality traits always persist, though, whether he's in hero-mode or normal-mode: his optimism and his oafishness. He has always had faith and hope that someone would come along, worthy enough to bear the "One for All" Quirk. He is sometimes depicted being outsmarted by his students, and even his fellow teacher, Shouta Aizawa has called him an idiot a few times.

While he is seen smiling, laughing, and cheerful most of the time, he was shown to be furious when he learned Villains were trying to get to him through his students. Even Izuku was surprised to see such a reaction. He was willing to use his Quirk beyond his time limit in order to save his students.

He possesses a fatherly attitude towards his students (Izuku in particular), which he often hides and keeps to himself. He is quick to give encouraging advice to them when the situation calls for it. He is proud of their accomplishments.

History
Before meeting his teacher, who had passed on One For All to him, Toshinori originally did not have a Quirk. Five years before meeting Izuku, Toshinori fought a very powerful villain known as Sensei, who used a Quirk known as "All For One", which resulted in critical injuries that set a limit on the usage of his quirk.

Entrance Exam Arc
All Might first appears when Izuku Midoriya is being attacked by a villain. He then uses Texas Smash on the villain, saving Izuku. All Might is glad to see that Izuku is all right. He then decides to leave, asking Izuku to continue to support him. However, he is forced to land after Izuku grabs on to his leg. After doing so, he tries to leave again, but Izuku questions him on whether he can become a Hero without a Quirk. All Might reverts back to his true form, shocking Izuku. He then tells Izuku that professionals must always put their lives at stake to save the day and thus cannot openly say whether it is possible to be a Hero without a Quirk as it may not be possible. All Might says that if Izuku cares about saving people, he can always go on to become a policeman, as in that way he can be responsible for putting the villains in jail (even though it is ridiculed). He tells Izuku that it isn't bad to dream, but warns him not to obscure the facts and then leaves. All Might then sees that he wasted time in talking with Izuku, causing the villain he defeated before to escape, saying to himself that he is pathetic. After seeing Izuku's bravery in trying to save Katsuki from the villain, All Might decides to step in and uses Detroit Smash to defeat the villain, saving both Izuku and Katsuki. All Might then appears before Izuku, saying to him that he thanks him and has a proposal for him. He tells Izuku that he was touched by Izuku's bravery for trying to save someone despite not having a Quirk and tells him that he too can become a Hero.

All Might tells Izuku that he is worthy to inherit his strength. He tells him that his Quirk can be passed down and that Izuku has been chosen by him to be the next one to inherit his Quirk. Izuku asks why he would give someone like him his Quirk, to which All Might responds that he has been searching for a successor for a long time and now has found someone that he doesn't mind giving his Quirk to, saying that he despite not having a Quirk, tried to save somebody and that he shined more than any of the other heroes. Thus, All Might's proposal is whether he wants to inherit the One For All Quirk from him or not. Izuku accepts All Might's proposal. All Might trains Izuku for the next 10 months, explaining to him that in order for him to inherit his Quirk, Izuku's body (vessel) must be strengthened to the point of being able to handle the Quirk's power. All Might trains Izuku at the Seaside Park, a place filled with trash and tells him that he will clean up all the trash as part of training his body to become stronger. After 10 months have passed, All Might tells Izuku that he is now a genuine vessel. He then decides to give Izuku his reward for working so hard for the past 10 months: the One For All Quirk, saying that he has earned it fair and square. All Might gives Izuku his reward (a piece of his hair) and tells him to eat it so that he can inherit his Quirk.

One week later, Izuku receives a letter that will determine whether he was accepted into Yuuei or not. Izuku opens the letter in his room and a screen with All Might on it appears. He apologies for not contacting Izuku earlier and informs him that he will be working as a teacher at Yuuei. All Might tells him that he did fine on the written test, but since he scored zero points during the practical test he has failed. However, All Might tells him that because he rescued someone during the practical test, he earned 60 points, meaning he has passed and, therefore, is accepted into Yuuei, much to Izuku's joy and happiness.

Quirk Apprehension Test Arc
All Might is seen secretly inspecting Izuku's participation in the pitch trial of the Quirk Apprehension Test, impressed with Izuku's focus of the One For All Quirk at the tip of his finger and for his quick thinking of using the One For All Quirk in the shortest time possible at the last moment as a workaround for not being adjusted to the Quirk. All Might approaches him, calling him a liar and says that he once expelled an entire new class of first-graders last year. All Might knows that he kicks students out with zero chances, finding it weird that he didn't expel Izuku on the spot and concludes to him that even he felt Izuku's raw potential. However, Shouta replies that Izuku's are above the "zero" mark and that it all. He continues to say that he can kick anyone out whose chances drop below that mark at any time, then leaves. All Might then says that they will never get along. All Might then appears as the teacher of the foundational hero studies, saying that they will have a battle of trial for the period. He tells his students that Yuuei have prepared their Hero Costumes and says to them to get changed into their costumes for the battle trial.

Battle Trial Arc
All Might explains to his students that they will be separated into Heroes and Villains for the battle trial and it will be a two on two team battle. He explains that in the battle trial, the villains will guard a nuclear weapon they intend on deploying and the heroes must stop them. He goes on to further say that the heroes can win by capturing the villains or reach the nuclear bomb before time runs out and the villains can win by capturing the heroes or keeping the core away from the heroes before time runs out. All Might then decides that the teammates and pairs will be chosen by lottery. After the lottery, All Might draws from the boxes and says that the pairs that will do battle are the heroes: Izuku and Ochako versus the villains: Katsuki and Tenya. He explains that the villains will go in the building first, then after five minutes, the heroes will go in. He tells them to go all out as it is a practical exercise, although he says that he will stop the battle trial if things get out of hand. All Might is seen in the surveillance room, saying to himself that Izuku won't get any special treatment from him and will grade him as harshly as the rest. All Might tells Katsuki to stop after seeing what his Hero Costume can do to amplify his Quirk and becomes worried for Izuku after Katsuki initiates a huge explosion.

All Might then tells Katsuki that if he uses another huge explosion, he will end the battle trial and he will lose, reprimanding him for trying to destroy the building that protects their stronghold (the core) calling it foolish. Although he feels that he should stop the battle trial, he thinks that it would be better for Izuku and Katsuki to continue battling as it is necessary for the future that they envision themselves. After being asked to stop the battle trial, All Might is about to suspend it, but after hearing Izuku call out to Ochako, he stops. After Ochako touches the core, All Might announces that the Hero team wins.

All Might approaches Katsuki, telling him that it's time for his critique. He tells Katsuki that it doesn't matter whether he won or lost, but that he takes one look back, reflect on his experience and move on with life. In the monitor room, All Might says that Tenya was the best during the battle trial. After being asked why, he questions his students as to why he chose Tenya. After Momo Yaoyorozu gives her answer, he gives a thumbs up to her for being absolutely correct. During the next battle trial, All Might is impressed by Shouto Todoroki for not getting him comrade caught in the attack and at the same weakened his opponents' positions as well as refrained from damaging the core. After everyone participates in the battle trial, he tells everyone that they did well and instructs them to change clothes and head back to class. Although he wanted to give Katsuki counseling for his self-confidence, he realizes that his transformation is running out of time and head to the nurse's office.

He is reprimanded by Recovery Girl for indulging his disciple, Izuku, too much and he says that he has nothing in his defense. They talk quietly, with him saying that his Quirk is secretly known by a selected few (including her). Recovery Girl asks if it is important to be a "Natural Born Hero" or "The Symbol of Peace" to which he replies that without such a symbol, the society of superhumans would fall to evil. She then tells All Might to be a better guide to Izuku. All Might then appears before Katsuki, trying to counsel him on self-confidence, although he is told in response by Katsuki that he will surpass him as well, thus All Might decides to leave Katsuki alone, finding that teaching can be difficult.

Ultimate Space & Jams Arc
All Might is seen using Missouri Smash on Vihara Headgear, defeating him and saving the family in the process. He then realizes that his Quirk is steadily dropping off, as the amount of time he can keep his Quirk activated has decreased. In a flashback, Izuku is seen speaking to All Might telling him that he revealed to Katsuki about the secret of the One For All Quirk. However, All Might isn't angry about it since Katsuki interpreted it as nonsense and tells Izuku to keep the secret to himself and no one else since if the villains knew about his secret, all of them would probably want to steal his Quirk. He then tells No. 13 that he won't be able to appear at the Ultimate Space and Jams due to him using his Quirk too much and then takes a nap. After his nap, All Might tries to contact, No. 13 and Shouta, but to no avail. He decides to go to the U.S.J, but Mr. Principal arrives to have a discussion with him, being held up by Mr. Principal's endless talking, seeing that he hasn't changed either. All Might then appears at the U.S.J, telling everyone to have no fear as he is there.

He says that he ran into Tenya and knows the gist about the situation. All Might quickly dispatches the villains in front of Shouta, apologizes to him and picks him up. He then rescues Izuku, Minoru, and Tsuyu. All Might asks the three to head to the entrance and leaves Shouta with them. When Izuku tries to dissuade him into fighting, Al Might tells him it's all right. All Might uses Carolina Smash on Noumu, but has little effect. He realizes that his blows are not having any effect against the villain. After hearing Shigaraki's information on Noumu, All Might uses a backdrop slam against Noumu, causing an explosion. However, Black Mist opens a gate with his Quirk, causing All Might's attack to fail and allows Noumu to grab All Might. However, the combined efforts of Katsuki and Shouto allow him to escape from Noumu.



All Might then blocks a punch from the regenerated Noumu, giving Katsuki some time to evade. All Might then calls Shigaraki's view on the title Symbol of Peace as rubbish. He then tells the children to escape, thanking Izuku for his concern and says that he is fine. Realizing that he has only a little time left, All Might decides to go all out. He and Noumu get into a fist fight and All Might sees that he can absorb each punch at 100%. All Might decides to surpass his 100% and launches a devastating punch against Noumu, sending Noumu flying out of the U.S.J, defeating him. Even though he is badly beaten and battered, All Might prepares to fight Shigaraki.

All Might asks why he is not going to fight since it is his mission to kill him. All Might then realizes that his fight with Noumu has completely left him powerless, not even having the strength to take another step. Shigaraki and Black Mist attack All Might, but Izuku intervenes to protect the powerless All Might. However, one of the heroes that Tenya called as backup stops Black Mist and Shigaraki from attacking him. When Izuku says he couldn't do anything, All Might says its not true, telling him that if it were not for his few seconds of bravery, he would be dead and thanks him for saving him.

All Might is then seen at Yuuei's Nursery, being treated by Recovery Girl. A detective arrives who All Might knows and asks him about the students' conditions, as well as Shouta and No. 13. The detective tells him that the students are unharmed, but Shouta and No. 13 are injured, but not in danger of death, relieving All Might worries. All Might tells the detective that the students fought bravely and that they will become great heroes, to which the detective agrees.

Sports Festival Arc
All Might is seen in the meeting room, commenting on Tomura's arrogance and when he started to panic when things went wrong. After taking Tomura's childish personality into consideration as well as his determination, All Might concludes to those in the meeting room that Tomura is a mere character who believes that he is the center of attention, an "adult-child". After the meeting, All Might finds Izuku and asks him to have lunch with him. In the resting room, All Might asks him how he is handling his Quirk and Izuku replies that he has gained adjustment to the Quirk, saying that he did not break his arm when punching Noumu, which pleases All Might.

He then tells Izuku that his time as the Symbol of Peace is heading to an end, much to Izuku's sadness. All Might says that Yuuei's Sports Festival is an event the whole country will be watching and tells Izuku that in the event he wants the whole world to know that he is the new generation's "All Might" and the future Symbol of Peace, shocking Izuku.All Might states that he wants Izuku to demonstrate his full potential to everyone at the Sports Festival. After Izuku doubts himself, All Might encourages him, stating that the difference between someone who aspires to the top and someone who doesn't will have a huge influence when he steps up and steps forward in society. All Might says that he understands Izuku's feelings towards his condition and won't force him to do anything, but asks him to remember his feelings during the time he cleaned up the Seaside Park.

At the Sports Festival, after Izuku places first in the Obstacle Race, All Might smiles and claps for him. All Might then ponders about Katsuki, thinking that his ranking in the Obstacle Race, combined with the sheer versatility of his Quirk makes him a popular choice for a teammate. Near the end of the Human Cavalry Battle, after seeing Katsuki using strategy to get Neito's last headband, All Might comments to himself that Katsuki, despite no one telling him, is grasping instinctively the difference between those who don't necessarily aim for the top all of the time and those who always do. After the lunch break begins, All Might in his hero form greets Endeavor, saying its been a while and asks him to have tea with him.

All Might says that they have not spoken to each other in ten years and that he wanted to give him a shout out, Endeavor replies that he can take his tea offer to some other place and tells him to go away. As Endeavor leaves, All Might stops him, saying that his son Shouto was able to show a great performance even without using half of his power. All Might then asks Endeavor for advice on how to raise the next generation. Endeavor comments on All Might's attitude, finding it to be annoying and then says that he will make Shouto a hero that surpasses All Might, then angrily walks away. All Might goes to see Izuku before the beginning of his match. After Izuku says that he can raise his strength only a little with One For All, All Might says that originally, on a scale of one to a hundred, the amount of strength Izuku's body could tolerate it was zero, but now it's a five. When Izuku starts frowning, All Might cheers him up; telling him to do his best and encourages him to smile when he is full of fear and anxiety. All Might then concludes that he is always watching Izuku. All Might goes to the infirmary to see Izuku, After Recovery Girl scolds All Might for putting pressure onto Izuku, Izuku tells All Might about the mysterious shadows he saw, saying that the shadows helped him break free of Hitoshi's mind control and asks All Might if what he saw were the people who wove the power of One For All. All Might replies that he too saw something similar to what Izuku saw in his younger days. All Might theorizes that the people he saw were imprints of those who have used One For All but not the sort who have a will on their own and concludes that Izuku broke Hitoshi's spell, not because of the predecessors of One For All but because his unwilling of willpower caused the vision to appear that broke Hitoshi's brainwash. Izuku isn't completely satisfied with the explanation, but All Might tells Izuku not to dwell on it and tells him to go watch the next match. After Izuku leaves, Recovery Girl says that Izuku also saw him in the vision, to which All Might replies that it is a good thing. During the match between Izuku and Shouto, All Might watches on, worried for his student's health. After Izuku states to Shouto that becoming Number One without his full strength as well as to disown someone is a joke, All Might remembers Endeavor's words of making his son surpass him. Soon after remembering, All Might theorizes to himself that Shouto won't use his fire power due to the discord between him and his father. He then tries to figure what Izuku is trying to do. After Shouto activates his fire power, All Might concludes that Izuku is trying to save Shouto from his cruel fate, despite wanting to win. All Might notes that Izuku is going out of his way to help his opponent, causing him to wonder which of them is the joke. After Izuku is defeated by Shouto, All Might goes to Recovery Girl's office to see Izuku. She scolds All Might for making Izuku push his limits and tells All Might not to try and praise Izuku for going so far. When Izuku apologizes to All Might for not living up to his expectations, All Might's face is filled with regret. After Izuku tells All Might that all he wanted to do was help Shouto and asking for forgiveness, All Might responds by saying that his match was simply an unfortunate outcome but praises Izuku for helping Shouto with his problem, saying that reaching out and helping people with their personal problems is one of the principal qualities of a Hero, happy that Izuku has such a quality. After Izuku's surgery is finished, Recovery Girl tells All Might to try and find a different method for Izuku to use his One For All. Izuku leaves Recovery Girl's room with All Might and they walk down the corridor. Izuku sadly tells All Might that he thinks someone else should be his successor. However, All Might tells Izuku that he used to be Quirkless just like him, which surprises Izuku. Izuku says to All Might that he never knew about that information causing All Might to reply that Izuku never asked him. All Might tells Izuku that he chose him to be his successor at first due to him being similar to his former self and admits to Izuku that he has surpassed his expectations after seeing Izuku's actions. He then says to Izuku that only he will be able to truly shine with the power of One For All. Having been cheered up by his mentor, Izuku apologizes to All Might. All Might tells him to watch the rest of the Sports Festival, to which he complies.

All Might, in his Hero form, appears at the closing ceremony of Yuuei's Sports Festival to hand out medals to the winners of the Freshmen Stage: Fumikage Tokoyami, Shouto Todoroki, and Katsuki Bakugou. All Might gives Fumikage his medal for placing third, congratulating and acknowledging his strength. He gives Fumikage a pat on the back and a congratulatory hug, telling Fumikage that in order to defeat his problem with unfavorable matchups he shouldn't always rely on his Quirk and that he should increase his own strength to deal with unfavorable matchups better. All Might gives Shouto his medal for placing second, congratulating him and understands that Shouto had his reasons for suppressing his fire side in the final match. After Shouto tells All Might that he must come to terms with things to solve his problems, All Might gives Shouto a congratulatory hug, saying to Shouto that he won't pry any further and that he knows fully well that Shouto can solve anything with his power. All Might then goes to give Katsuki his medal for first place, finding the restraints to be a little too much. All Might takes Katsuki's face mask off, causing Katsuki to angrily yell that he doesn't deserve to be Number One. However, All Might tells Katsuki that society will acknowledge him as Number One even if he doesn't. All Might gives Katsuki his medal. Afterwards, All Might gives a speech to everyone; saying that everyone who participated in the Sports had a chance to stand on the podium. He goes on to say that the future generation of Heroes looks bright. All Might yells out "Great Work", much to the confusion of the crowd who thought he would yell "Plus Ultra", causing him to reply that he thought "Great Work" would be far more appreciative.

Field Training Arc
All Might is in Yuuei's Faculty room. Cementoss informs All Might that a new nomination has just arrived for the freshmen, telling All Might that the nomination is for Izuku. Excited, All Might goes to check who nominated Izuku. As he checks, All Might becomes flabbergasted at the person who nominated Izuku.

After school that day, All Might appears in front of Izuku as he is about to leave class. All Might and Izuku walk along the corridor. All Might says that Izuku received a nomination, much to Izuku's surprise. All Might tells Izuku that the person who nominated him was Gran Torino. All Might explains that Gran Torino was a Pro Hero who taught at Yuuei for one year and that Gran Torino was his homeroom teacher. All Might says that Gran Torino was a close friend of his predecessor, but now he is in retirement. All Might says that Gran Torino knows about the One For All Quirk which is the reason why he must have nominated Izuku. Shaking nervously, All Might wonders if Gran Torino was compelled to nominate Izuku due to him thinking that his guidance towards Izuku was lacking, becoming terrified by the fact that he is taking up his Hero name again. While trying to stop his legs from shaking, All Might tells Izuku that while it is his duty to train him, he should select Gran Torino as his work place of choice and see what he can learn from him. Before leaving, All Might informs Izuku that his Hero costume has been repaired.

Naomasa meets with All Might at Yuuei. He tells All Might that the Police Force has tried everything to get information out Noumu, however, everything they tried did not work. Naomasa says that they instead looked into Noumu's background through DNA analysis and have discovered that Noumu was once a human with a criminal record. Naomasa explains that the DNA analysis also revealed that Noumu has the DNA of at least four different humans mixed with his own. Naomasa concludes that Noumu is an artificial human made to measure up to multiple Quirks and that having all the DNA in his body as well as his body modified caused Noumu's brain activity to stop. Naomasa tells All Might the real issue is that Noumu's DNA is of primary concern because it contains multiple Quirks. Naomasa says that Noumu could not have acquired multiple Quirks in any way (unless Noumu acquired the Quirks through advanced genetic familial permeation. Naomasa comes to the conclusion that someone with a Quirk that can grant Quirks is behind Noumu's acquisition of multiple Quirks. All Might becomes concerned.

After Stain's defeat is published, Gran Torino speaks to All Might using a telephone. Gran Torino expresses his annoyance that his pay has been cut in half and his right to teach is revoked for half a year but says that considering the circumstances he doesn't mind. Gran Torino tells All Might that Izuku has improved drastically in using One For All, saying that Izuku movements are similar to his own; All Might apologizes profusely and thanks Gran Torino for his help, admitting that his teaching towards Izuku has been inadequate. Gran Torino says that he only became qualified as a teacher so that he could keep his promise to Shimura, All Might's predecessor. All Might thanks Gran Torino for everything as he wouldn't be the man he is today without him; Gran Torino yells that All Might forgot about him, to which All Might says that he never forgot. Gran Torino tells All Might that he is calling him about the encounter with the Hero Killer; he admits that Stain's strong ideology is similar to All Might's. Gran Torino says that if Stain's backstory is revealed to the public through the use of media, villainy will rise and the Villain Alliance will take credit as a group following Stain's ideology due to the connection between them which will cause delinquents to join the Villain Alliance. Gran Torino states that he believes that an old enemy will use Stain's backstory to remove obstacles in his path. Gran Torino hypothesizes that the old enemy, the villain who killed All Might's predecessor and gave All Might his scars, "All For One" has returned. All Might is in disbelief that "All For One" has returned, not wanting to believe it. Gran Torino advises All Might to reveal to Izuku everything about himself and One For All when the opportunity arises.

The workplace training comes to an end and Class 1-A returns to Yuuei. Class 1-A next class is Foundational Hero Studies with All Might. All Might says that their lesson will be a rescue training race through Playing Ground Gamma (a construction site with many densely packed lanes which makes it look like a labyrinth). The class must race through the construction site and to the area in the middle to meet up with All Might. Class 1-A will split into four groups of five for the training lesson. Izuku, along with Ojiro, Tenya, Mina and Hanta are the first group that will partake in the rescue training race. All Might watches the race and is surprised at Izuku's movements. After the race ends, All Might commends the group on improving their Quirks more broadly since entering Yuuei. He asks them to prepare for the end-of-term test. All Might then approaches Izuku, telling him that he is impressed with his improvement and gives him a thumbs up. All Might tells Izuku that after the lesson is finished, he should come to his place because he wants to talk to Izuku about the story of him and One For All.

All Might meets with Izuku in the Break Room. All Might tells Izuku to lock the door and then apologizes to Izuku for not being at his side during the Hosu incident, to which Izuku replies that he doesn't have to apologize. All Might says that Izuku's blood was ingested by the Hero Killer, reminding Izuku about One For All transfer and inheritance method, causing Izuku to panic (thinking that One For All is in Stain's possession). However, All Might tells Izuku that he still has One For All because One For All won't be transferred to a new recipient unless the user wishes it, thus One For All cannot be forcibly stolen, although it can be forcibly passed on. All Might tells Izuku that One For All is a special Quirk and begins telling izuku One For All's origin. All Might says that One For All is derived from a Quirk that has existed since the beginning.

All Might says that long ago during the Quirk phenomenon, society had not adapted to the idea of having Quirks which caused an age of upheaval to arise; a man possessing a Quirk called All For One (a Quirk that can steal Quirks and grant them) stole many Quirks and used his new overwhelming power and influence to gather and unify people under his command. The man used the people he gathered as pawns for his plans which allowed to take over Japan and made himself its evil ruler. Izuku says that he has heard rumors but this story is not in any textbook causing All Might to reply that underground dealings are never recorded in the textbooks. Izuku asks how this man is related to One For All. All Might says that All For One can grant Quirks, but those who were not able to handle the strain became brain-dead like Noumu. All Might explains that there were cases for those who did survive the procedure where their Quirks mutated. All Might tells Izuku another story; the man (who would eventually become Japan's evil ruler) had a younger brother; the man used All For One and forcibly gave his younger brother a Quirk that stockpiles power. However, the younger brother already had a Quirk, a Quirk that can transfer itself to others. The younger brother's Quirks (one that stockpiles power and the other that can transfer itself) merged together and became One For All.

All Might notes the irony that justice was born in the bowels of evil. Izuku says that it is impossible for the man who ruled Japan in the distant past to be alive. All Might theorizes that the man stole a Quirk that stopped his aging or a Quirk that granted him immortality. All Might explains that the younger brother, whose Quirks became One For All, fought against his older evil brother but could not defeat him. The younger brother decided to pass on One For All to the next generation so that one day it will accumulate enough power to defeat the older brother's All For One; All Might says that he was finally the successor that defeated the older brother, or so he thought. All Might tells Izuku that the man possessing All For One has returned and is leading the Villain Alliance. All Might finishes his story by saying that One For All is a power that is meant to stop All For One and that Izuku will also have to confront the man.

All Might apologizes for giving Izuku so much information. Izuku says that whatever task All Might gives him he will accomplish no matter what as long as All Might is by his side. All Might isn't able to bring himself to tell Izuku that he won't be able to remain by his side when the time comes and thanks him instead.

End of Term Test Arc
Izuku and Katsuki are paired together and must fight All Might in their end of term test exercise. All Might tells the wonder duo to cooperate together and come at him to win.

All Might, Izuku and Katsuki get onto a bus and drive to an uninhabited city where the test exercise will take place. All Might, Izuku and Katsuki arrive in the city. All Might explains the test exercise: Izuku and Katsuki have two options of winning and passing the test exercise; they must either handcuff All Might or one of them must escape from the battlefield. Izuku and Katsuki have to accomplish either fighting to handcuff their opponent or one of them must escape the battlefield in 30 minutes. Izuku notes that this will test their flight or fight decision skills. All Might puts on super compact weighted bracelets to give himself a handicap. The test exercise begins. After a while passes, Izuku and Katsuki begin arguing. Suddenly, All Might throws a punch which devastates the area Izuku and Katsuki are in; All Might says that he will have to get involved.

Izuku is shocked at the level of All Might's (even though he knows that All Might is handicapped and severely weakened to begin with). All Might declares to the duo that he is a villain and collateral damage means nothing to him. All Might charges at the duo. Feeling All Might's pressure, Izuku tells Katsuki that they have no chance of winning and should run away. However, Katsuki refuses to run away. Katsuki uses Stun Grenade against All Might which distracts him. Katsuki charges at All Might, but the Symbol of Peace grabs Katsuki's face, stopping his advance. Katsuki launches a flurry of Explosions against All Might. However, Katsuki's Explosions do not even scratch All Might. All Might slams Katsuki down onto the ground. All Might turns his attention to Izuku who planned on running away. All Might questions Izuku on his decision to escape. Izuku recalls the Hero Killer and activates One For All Full Cowl, wondering why he suddenly recalled the Hero Killer. Izuku jumps into the air, but Katsuki has also jumped into the air; the duo collides into each other as a result.

All Might appears in the air with a guardrail in his hands; All Might slams the guardrail on Izuku which pins him down to the ground. Then, All Might punches Katsuki in the stomach, greatly injuring him and sending him flying backwards. All Might approaches Katsuki and says that he understands his jealousy of Izuku's sudden growth; All Might tells Katsuki that what he is currently doing is a waste and must grow his willingness to borrow other peoples' strength. The weakened Katsuki struggles to get up and tells All Might that if he must rely on other peoples' strength, then he would rather lose. Disappointed with Katsuki's decision, All Might prepares to finish off Katsuki; Katsuki tries to move but to no avail. Suddenly, Izuku activates One For All Full Cowl and breaks free of the guard rail; Izuku charges and punches Katsuki out of harms way.

All Might chases after Izuku and Katsuki. Suddenly, Katsuki appears from behind and attacks All Might with an Explosion which distracts All Might. However, one of Katsuki's Grenade Bracers is missing. Suddenly, Izuku appears behind All Might with Katsuki's missing Grenade Bracers equipped on him. Katsuki yells at Izuku to commence his attack; Izuku aims the Grenade Bracer at All Might and releases the grenade pin.

Izuku releases the grenade pin and blasts an immense Explosion at All Might at point blank range. After the Explosion is finished, Izuku and Katsuki dash towards the exit. All Might easily takes the Explosion, only coughing up a little blood. All Might is impressed with the duo's strategy; All Might notes that while their relationship will not improve immediately, Izuku and Katsuki's cooperation with each other in this practical test will be a great leap forward for them in the future. All Might decides to chase after the escaping Izuku and Katsuki, declaring that he will give it his all.

All Might catches up to Izuku and Katsuki and defeats them; All Might pins Katsuki down on the ground with his foot and dangles Izuku in the air with his arm. All Might praises Izuku and Katsuki for working together to try and defeat him but reminds them that working together is merely a per-requisite of the practical test.

Recovery Girl announces that Shouto and Momo are the first team to pass the exam. All Might is surprised to learn that his colleague, Shouta, has been defeated. All Might smashes Katsuki into the ground with his foot. Katsuki finally understands that All Might is far too overpowered for him to stop and realizes that All Might is truly the strongest Hero and the world's most sky scrapping wall. Izuku tries activating One For All Full Cowl, but All Might stops him and throws him onto the ground. All Might decides to finish off Izuku and Katsuki.

Suddenly, Katsuki gets up and launches a big explosion against All Might, which distracts the Symbol of Peace. While All Might is distracted by the light, Katsuki grabs Izuku and throws Izuku towards the escape gate with an Explosion. To prevent Izuku from escaping, All Might uses New Hampshire and blasts himself into Izuku which crushes Izuku due to All Might's great weight and sends him tumbling down. Katsuki chases after All Might; Katsuki tells All Might that the Grenadier Bracers were to help him use his maximum Explosions without risk and admits that he was a fool for thinking that he could win without taking risks. Katsuki uses a huge Explosion against All Might (similar to the Explosion in the Sports Festival) and tells Izuku to escape; Izuku struggles to get up. Katsuki decides to sacrifice himself to hold off All Might so that Izuku has time to escape; Katsuki uses another huge Explosion against All Might. However, although the great Explosions have distracted All Might, the Symbol of Peace is still unscathed.

Izuku gets up and prepares to activate One For All Full Cowl so that he can leap towards the escape gate. Not allowing Izuku to make an escape, All Might prepares to attack Izuku but Katsuki intercepts All Might's attempt. Izuku successfully activates One For All Full Cowl and begins his escape while All Might smashes Katsuki into the ground. Izuku sees that Katsuki is in trouble. Despite being greatly injured, Katsuki yells at Izuku to escape and bites All Might's hand. All Might ignores Katsuki's desperate attempt and tells Izuku that he won't allow him to escape.

Surprisingly, Izuku does not rush towards the escape gate; instead, Izuku rushes back to help Katsuki. While rushing to help, Izuku remembers All Might's words; that when times are scary and uncertain, you face it all with a smile. Izuku smiles and punches All Might in the face. While All Might is suffering from slight recoil, Izuku grabs Katsuki who has fallen unconscious. Izuku rushes towards the escape gate with Katsuki in tow. All Might shrugs off Izuku's punch and watches him escape. All Might understands by now that Izuku is the type of person to save somebody; All Might notes that whenever Izuku tries to save somebody, there's never a wall in his way.

After Izuku and Katsuki pass the practical exam, All Might carries them to Recovery Girl's tent to be healed. Recovery Girls scolds All Might for not restraining himself during his battle with Izuku and Katsuki. Recovery Girl asks All Might to take Izuku and Katsuki back to Yuuei to recover. After Izuku requests to stay, All Might leaves carrying an unconscious Katsuki in his arms, he notes that Izuku will be extraordinarily strong one day. All Might walks out of the tent and prepares to carry Katsuki back to Yuuei. All Might notes that Katsuki himself is also incredible and that whenever there is a wall in front of Katsuki, he laughs at it.

School Trip Arc
After The Hero Incident involving Izuku occurs, All Might goes to the Police Station. Outside the Police Station, All Might greets Izuku and Naomasa; All Might apologizes to Izuku for not being there. Thinking about his conversation with Tomura, Izuku asks All Might if there were times when he failed to save someone. All Might tells Izuku that there were many times he couldn’t save someone; All Might modestly admits that he is only human and cannot save everyone. All Might notes that his title, the Symbol of Peace, serves to inspire people and Heroes to play their roles so that more people can be saved. Izuku’s mother arrives to pick Izuku up; Izuku comforts his crying mother, telling her that everything is fine. After Izuku and his mother leave, Naomasa theorizes that Tomura will probably target other students and decides that Hero schools must exercise more caution and become more proactive in implementing counter measures against villains. Naomasa advises All Might that leaving Yuuei is also an option, but All Might decides against it. Naomasa concludes their conversation by saying that they will capture All For One this time, to which All Might agrees.

Quirk and Abilities
One For All (ワン・フォー・オール): All Might's Quirk grants him superhuman strength, superhuman speed, greatly enhanced agility, enhanced reflexes, high durability and the ability to jump really high.
 * Texas Smash (テキサススマッシュ): All Might throws a right punch with enough force that the wind pressure sends anything made of liquid flying away. This move was first used to save Izuku Midoriya from an unknown enemy in Chapter 1.
 * Detroit Smash (デトロイトスマッシュ): All Might preforms that same attack as Texas Smash except this move is with a downward punch instead of a straight punch, the punch is powerful enough to create a shock wave large and powerful enough to clear the weather. This move was first used to save Izuku Midoriya and Katsuki Bakugou from an unknown enemy in Chapter 1.
 * Missouri Smash (ミズーリースマッシュ): All Might runs towards an enemy while keeping his hand flat and hits the enemy on the head while running past them. This move was first used against Vihara Headgear in Chapter 13.
 * Carolina Smash (カロライナスマッシュ): All Might runs towards an enemy while keeping his hands in a cross position, then in a downwards cross chop to the enemies head. This move was first when against Noumu in Chapter 18.
 * New Hampshire Smash (ニューハンプシャースマッシュ): All Might blasts himself towards his enemy and smashes his body into the enemy, crushing and injuring the enemy with his great weight. This move was first used in Chapter 65.

Immense Strength: All Might is an extremely powerful Hero as he is recognized as the "Symbol of Peace", indicating his extraordinary and immense power. He was able to defeat Noumu (who was created specifically to combat All Might) despite Noumu having Quirks that gave it an advantage over All Might. Despite becoming severely weakened since his first meeting with Izuku, All Might was able to cause collateral damage to a city block with one punch while being handicapped with great weights. All Might, despite his weighted handicap and depleted strength, was able to easily overwhelm Izuku and Katsuki, who are among the strongest in Class 1-A.

Immense Speed: In conjunction with his immense level of physical strength, All Might possesses an equally impressive amount of speed. During the USJ Arc, he was able to travel a remarkable distance from the gate and simultaneously incapacitate five villains in the blink of an eye. He could disappear from Tomura's sight and strike him and intercept Noumu while the latter was about to attack Katsuki, despite Noumu's showing of being on All Might's level himself.

Immense Durability: All Might has extreme durability. During the villain's invasion of the USJ, he could manage to block a direct attack from Noumu, and later take many attacks from him during their physical bout. During his fight with Izuku and Katsuki in the End of Term Test Arc, he was able to take several of Katsuki's unrestrained attacks with his Quirk without as much as being slowed down.

Equipment and Weapons

 * High Density Weights (Combat Exam Arc) - All Might and the rest of the teacher used these bracelets to give themselves a handicap while they fought their students.

Battles
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 * All Might vs. Sensei: Win

Entrance Exam Arc

 * Izuku Midoriya and All Might vs. Villain: Win

Ultimate Space & Jams Arc

 * Kamui Wood, Mount Lady & All Might vs. Vihara Headgear: Win
 * All Might vs. Noumu, Black Mist & Shigaraki Tomura: Lose
 * All Might, Izuku Midoriya, Katsuki Bakugou, Shouto Todoroki & Eijirou Kirishima vs. Villain Alliance: Win

End of Term Test Arc
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 * Izuku Midoriya & Katsuki Bakugou vs. All Might: Lose

Izuku Midoriya
At their first meeting, All Might thought that Izuku was just a fan, but he started to acknowledge him when he jumped to save Katsuki from the Hedoro Villain. From that moment, he was touched by Izuku's bravery (despite not having a Quirk) and decided he would pass his powers to Izuku, feeling that he is the only one worthy enough to inherit his strength, and they started to share a feeling of mutual respect for each other.

Shouta Aizawa
Not much is known of their past, but due to their contrasting personalities, they don't get along very well.

Recovery Girl
Recovery Girl is one of All Might's friends that know about his condition and his Quirk.

Mr. Principal
Mr. Principal is another of the few people that knows of his condition and was the person that offered him a teaching position at Yuuei.

Naomasa Tsukauchi
Naomasa Tsukachi is also another person that knows about his condition; All Might thinks he is the best cop there is.

Endeavor
Ten years before the start of the series, All Might once had a talk with Endeavor and since then, they have not spoken to each other. All Might appears to respect Endeavor, wanting advice from him on how to raise the next generation. It seems that their rivalry is mainly one-sided (on Endeavor's) as All Might is usually friendly with him.

Trivia

 * All Might's real name contains the kanji for "genius" (俊) and "ceremony, celebration" (典).
 * All Might likes movies.
 * All Might's signature moves are named after states and cities in America.
 * In the First Popularity Poll, All Might ranked 5th, which currently makes All Might the most popular Pro Hero and Yuuei teacher in Boku no Hero Academia.
 * All Might has a habit of calling those who are younger than him "My boy", in his mind or while talking to them directly.

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