| “ | The first person cultivates the power, and then passes it on to another. The next refines it and passes it on again. In this way, those crying out to be saved and those with brave and true hearts link to form a crystalline network of power! | „ |
| ~ One For All described to Izuku Midoriya by Toshinori Yagi in Roaring Muscles |
One For All (ワン・フォー・オール Wan Fō Ōru?) was the major aspect of the superhero anime/manga series, My Hero Academia. It was the transferable Quirk that was possessed by its ninth user, Izuku Midoriya.
In the past, it was originally used by Yoichi Shigaraki, and later, its other previous hosts: Kudo, Bruce, Hikage Shinomori, Daigoro Banjo, En Tayutai, Nana Shimura, and Toshinori Yagi. Izuku forcibly transferred the Quirk to Tomura Shigaraki via blood transference, and as a result, the Quirk was destroyed and became unusable. It was also briefly used by Katsuki Bakugo.
History[]
A long time ago, two brothers were born, with the oldest possessing a Meta Ability that allows him to steal other people's Abilities and transfer them to others, while the younger brother seemingly did not have one. The oldest brother, now called All For One, rose to power while his younger brother, Yoichi, who was weak and frail due to a very fragile body, opposed his brother's rule. Angered by Yoichi's defiance and in a twisted show of affection, All For One forced onto his younger brother a Quirk that allowed him to stockpile power within his body. However, unbeknownst to him, Yoichi already had a Quirk with no other power than to transfer it to another person. The transference Quirk and the power stockpiling Quirk merged to form One For All.
Yoichi was freed from All For One's grasp by a resistance leader named Kudo and his second-in-command, Bruce. Eventually, his brother managed to track them down in an attempt to reclaim him, and when they tried to flee, All For One killed him. Yoichi's blood splattered all over Kudo as he and his resistance escaped, and shortly afterward he began feeling weird effects in his body. Bruce examined him and discovered that alongside his original Quirk Factor, there existed another, almost insignificant, Factor as well, which Kudo realized was Yoichi's lingering will, having passed on within him. All For One came to this same conclusion after discovering Yoichi's Quirks to be missing from the remaining left hand he had kept of his body, and realized Yoichi was still out there.
After these events, the Quirk would become entrusted to the future generations of Heroes, with the hope that they would be able to cultivate the power, now known as "One For All", and one day put a stop to All For One. Meanwhile, the Villain made it his mission to track down the users of the Quirk all to reclaim Yoichi, whom he considered his "first possession". He tracked down and killed Kudo, who had already transferred the Quirk to Bruce, and later killed him as well, only for him to have already passed it along as well.
The fourth user, Hikage, believed that he would not be able to defeat All For One and decided to use his "turn" with One For All to seclude himself and train the Quirk to be as strong as possible. However, after eighteen years, his body unexpectedly started to deteriorate. Though he blamed it on an unknown disease at the time, in reality, possessing One For All and his original Quirk had dramatically shortened his lifespan, forcing him to pass it on shortly before dying. All For One attempted to steal One For All twice, first from the fifth user, Daigoro, and then from the sixth, En, but failed both times. This failure was because the Symbol of Evil couldn't muster the hatred to overcome the fragments of the wielders' consciousness.
Each of these times the users managed to pass on the Quirk to the nearest hero they trusted right before they were killed by All For One's hand; Daigoro giving it to En, and En to the seventh user, Nana. She ended up being the first One For All user to choose an apprentice to pass the Quirk along to, that being the Quirkless Toshinori. She transferred the Quirk to him, and several years later, also met a grisly fate by All For One. Toshinori eventually managed to reach the level of power in One For All that allowed him to defeat All For One in battle, but suffered critical injuries in the process. Despite his injuries and the pleading of his friend and sidekick, Sir Nighteye, Toshinori continued fighting for another six years before picking a successor, putting the Symbol of Peace's tenure as One For All's wielder at 40 years.
After much deliberation in choosing a successor and being scheduled to teach at U.A., which would help Toshinori find one, he encounters Izuku, a Quirkless boy just like he was. Impressed with Izuku's drive to become a hero and his selfless spirit, Toshinori chooses him to become the ninth and current wielder.
While the Quirk was initially perceived as primarily a source of tremendous power, things started to change as Izuku became more accustomed to the Quirk, and it reached the "point of singularity". Not only did the consciousnesses of the previous users gain a more physical form within a vestige realm that could communicate with each other and Izuku, when prior they were only echoes seen in dreams, but also the Quirks of the predecessors emerged from One For All's core, allowing Izuku to use them.
This sudden growth led to Toshinori researching the users' past to find any information to aid Izuku. It was here when he discovered the autopsy behind Hikage's death, and while he was unsure about it at the time, Toshinori speculated that he'd been able to continue using One For All for so long because, unlike most of its other wielders, he was Quirkless.
Due to this revelation, according to Yoichi, Izuku might be the last user of One For All, as it can only be handled by someone who was originally Quirkless, considering said population has dramatically decreased through the generations. The Quirk has been passed down through nine generations, growing stronger. Currently, One For All is one of the most powerful Quirks in existence; however, it proves very difficult to master fully.
To steal One For All, All For One decided he needed someone with highly malicious intent, powerful enough to overpower the will of both the wielder and the other consciousnesses within One For All. He groomed Tomura Shigaraki for that purpose and filled him with hatred. Then, All For One transplanted his original Quirk onto Tomura and seized control of the younger villain. Using Tomura's will, All For One attempted to steal One For All from Izuku but was thwarted by Yoichi and Nana. Knowing that Tomura's body was still incomplete, All For One retreated and began to wait for its completion.
Very few were informed of One For All's true nature, fearing what villains would do if they found out that the world's most powerful Quirk could be transferred, as well as discourse among fellow heroes and the general public. Other than the users, All For One, and his confidant Kyudai Garaki, the only known people who knew the truth were Nana's partner Gran Torino, Toshinori's sidekick Sir Nighteye, U.A. staff Principal Nezu and Recovery Girl, and police detective Naomasa Tsukauchi. After Izuku nearly gave away the secret to Katsuki Bakugo out of guilt, the latter managed to deduce most of the truth, with the rest explained to him by Toshinori.
Description[]
One For All was a transferable Quirk that could be passed on from one user to the next. Its name came from its nature: being "one" Quirk for "all" people. For the Quirk to be transferred, the recipient must ingest a sample of the predecessor's DNA (ex: a strand of hair or a drop of blood).
The origin of One For All is itself a powerful will that refused to submit to All For One. For this reason, One For All cannot be stolen by any means. The Quirk can only be transferred to another person if the current wielder intends to pass it on, as demonstrated when Stain ingested some of Izuku's blood but did not inherit the Quirk. However, according to All Might, while One For All cannot be stolen, it can be forcibly transferred, as the recipient need not agree to inherit the Quirk in the first place. Since One For All can't be forcibly taken, it is one of the only Quirks that can be used in combat against All For One, as any user of All For One would be able to steal most other Quirks.
One For All also allows the user to stockpile an enormous amount of raw power, allowing them to significantly enhance their physical abilities to a superhuman level, resulting in unbelievable strength, speed, agility, and durability.
The user can focus the stockpiled power into a single body part or spread it evenly throughout their body, although focusing the energy puts a tremendous strain on the part of the body where the power is concentrated. The user can also control the percentage of the power they activate. One For All can even grant the user an exceptional strength boost to their given Quirk if they have one.
The core of One For All has grown in strength from being passed from user to user, and the Quirk Factors of all of the previous users have merged into the core. The current user, Izuku Midoriya, can access the Quirks of the previous One For All users. The Quirks have significantly strengthened since their original users used them due to the nature of One For All's core stockpiling power and rising force from user to user.
In addition to the Quirk Factors merging with the core, One For All carries "shades", or vestiges, of all previous users. Within One For All is a subconscious realm where the prior users can manifest, as fragments of their very consciousnesses are engraved into One For All. Originally, according to All For One, like organs and cells, Quirk Factors were said to contain the raw spirits, or the "individuality", of their users, which is then merged into One For All; however, the validity of this statement is brought into question by Yoichi, using the Quirkless Toshinori as counter-evidence.
Initially, the "vestiges" are merely masses of light that vaguely resemble their templates. However, upon the template's death, the said vestige becomes solid and conscious, able to converse with the other vestiges and current wielder of One For All. It was initially believed that these "vestiges" can only be embedded into One For All if the user possesses a Quirk; however, Toshinori proved this to be false since he didn't have a Quirk or a Quirk Factor to have his consciousness copied into, Toshinori instead was able to imbue a piece of his consciousness inside of One For All. This embedment allows the fragment conscious to fully interact with the other users and shares with them everything the real Toshinori knows, which is how the other vestiges were able to learn about the life-shortening side-effect of One For All on those who already wielded their own personal Quirk.
Weaknesses[]
When One For All is transferred, the new user's body is not naturally suited to it as they usually would be with a Quirk they were born with (ex: someone who breathes fire doesn't burn their mouth while using their ability). In addition, One For All is a lot to handle; if one's body can't take the power, then one's body could be blown apart. Because of this, the successor must undergo intense and rigorous physical training.
Even after inheriting the Quirk, it takes time for the new user to adjust to One For All and learn how to properly control it. While Izuku trained his body into a suitable vessel for the Quirk, it was rushed to a period of ten months for him to be ready for U.A. High School's Entrance Exam. Inexperienced use of the Quirk can easily lead to self-injury, most notably with Izuku, who could only use it in short blasts of power that would break his limbs. Only when Izuku learned to channel One For All's power evenly throughout his whole body was he able to stop this self-injurious habit and begin honing the Quirk's power as his own. Even so, repeatedly damaging his body led to extreme consequences, such as the ligaments in his arms becoming frailer, to the point where he now risks losing total function of them should he continue to use One For All recklessly.