Spoilers await around every corner.
The Story of Toshinori Yagi
Childhood
Toshinori Yagi was born quirkless on June 10th in Tokyo, Japan, into a world already buckling under the influence of All For One. Though there is no mention of his father, we know that he was raised by his mother, Toshie Yagi, depicted by Horikoshi as a loving woman who clearly had a close relationship with her son. Toshie read Anpanman and other books to him as a child which likely served to plant the seeds of his future vision.
As an adolescent, tragedy struck and left him an orphan. In his own words, “My family was killed awhile back.” We are never told the details of what led to this event, but we do know that it stoked the fire that pushed him forward.
As a teen, he crossed paths with Nana Shimura – the 7th holder of One For All. She saw this quirkless boy armed with a pipe and an unyielding resolve, ready to take a stand. He answered honestly when Nana questioned him. He had no desire to dwell on the hatred or seek revenge. Instead, he wanted to change the world itself and end the cycle where people who take from others always come out on top.
In that moment, Toshi told her the vision that would define his entire life. “The world needs a symbol. A Symbol of Peace.” From there, Nana became his mentor, passing on One For All and setting him on the path to become the symbol he wanted to become.
Forging A Hero
After inheriting One For All, Toshinori entered U.A. High School and trained under the guidance of Nana Shimura. She not only sharpened his abilities but also nurtured the ideals that had first drawn her to him: To become a hero who embodied hope, not vengeance. To him, she was much more than a mentor; she was like a mother.
Unfortunately, his time with Nana was tragically cut short. When he was eighteen years old, Nana was killed in battle against All For One, leaving Toshinori with a tremendous responsibility, but one he accepted without hesitation.
Honoring Nana’s request, Gran Torino stepped in to continue Toshinori’s training. Upon graduating, he urged Toshi to head for the US to gain both experience and distance from All For One. It is there he began the next stage of his journey: Training, building skills and preparing for the day he would rise as the Symbol of Peace.
In the USA
During his time in the US, he formed a close friendship with David Shield, a brilliant scientist who would go on to support him throughout his career, developing costumes that became synonymous with All Might. Even as a young hero, Toshinori’s actions left a lasting impression and inspired others, including the future hero who would come to be known as Star and Stripe.
The time Toshinori spent abroad left a lasting impact on him, shaping not only his approach to heroism but his identity as All Might. His admiration for the country would carry on into his personal interests and public persona alike, reflected in his love of film and in the naming of several of his hero attacks, such as Carolina Smash, Detroit Smash and United States of Smash.
Returning to Japan
After returning to Japan, he jumped into hero work with both feet, but remained in contact with David Shield, one of the few close friends he would ever have. Even his daughter, Melissa, referred to Toshinori as “Uncle Might.”
With an unyielding commitment to the people and a desire to bring peace to the world, he was able to bring the crime rate below 6%, ushering in one of the most peaceful eras Japan had ever seen. Villains feared him and civilians adored him, eventually earning him the top spot on the Hero Charts as well as the title of “The Symbol of Peace.”
Might Tower
While we aren’t given all the details to the timeline of his past, we do know that he established his own hero agency. Known as Might Tower, it was located in the Roppongi district of Minato Ward, Tokyo, Japan.
Taking on a Sidekick
In general, he made it a rule to not team up with other heroes, not wanting to be burdened down with the distraction of a sidekick. However, an exception was made when he crossed paths with Sir Nighteye.
A superfan in his own right, Nighteye formed a close friendship and earning enough trust through persistent loyalty that Toshi confided in him about the secret to his quirk. As a bonus, All Might didn’t have to worry about the paperwork associated with hero work, which was something he always felt took away from the time he could be using to save others in need.
Sir Nighteye’s quirk, “Foresight,” allowed him to see into someone’s future once a day for one hour if the right conditions were met. We aren’t told the details of how this usefulness assisted All Might, but we do know that Toshi had asked one thing of him: To never use his foresight on him.
Over the years, All for One’s influence resurfaced, leading to repeated clashes between the two. At some point while he was working with Sir Nighteye, about 5 years prior to the events in Season 1 of My Hero Academia, All Might gravely injured All For One. The victory came at an enormous cost as Toshinori lost his stomach and a lung in the fight. The injury permanently altered his life and career, forcing devastating limitations on the length of time he could transform into All Might each day.
It was at this time that Sir Nighteye used his foresight on All Might, viewing a horrifying future that shook him to his core: In 6 to 7 years time, All Might would face his greatest challenge and fall for the first time, losing his life in the process. Furious with Nighteye for breaking his trust, All Might cut ties with him and continued to work alone during the few hours a day he was able to while operating as the head of Might Tower in his weakened form as Toshinori Yagi the rest of the time.
One thing was clear, though. It was time to find a successor and pass on the power All Might had held onto for so long.
The Search For A Successor
Toshinori continued to appear as All Might whenever he could, preserving the image of the Symbol of Peace for as long as possible. With the knowledge that he needed to pass the power on, he eventually returned to the school that helped to build the hero that Japan depended upon. The principal at U.A. High School, Nezu, invited All Might to take on a teaching role, hoping that he would be able to find a worthy successor.
Before his tenure at U.A. officially began, Toshinori crossed paths with a boy named Izuku Midoriya through a chance encounter. Though he initially dismissed the quirkless boy, he witnessed Izuku move instinctively towards danger, driven by the singular need to help another.
Deeply moved, he sought out Izuku to offer him the power of One For All. A dream come true, Izuku accepted and over the course of several months, he was trained and mentored by All Might before successfully being accepted into U.A. Toshi continued to divide his time between teaching at U.A., mentoring his successor and performing hero work whenever his body allowed.
Kamino Ward and the End of an Era
All For One unexpectedly resurfaced during a rescue mission to bring Bakugo home. It was in the Kamino Ward where All Might pushed himself beyond his limits, exhausting the last embers of One For All to become victorious, but the outcome was devastating.
Though All For One was defeated, it came at the cost of Japan’s number one hero. All Might was forced to retire, marking an end of an era and leaving the nation to face an uncertain future without the Symbol of Peace. In the aftermath of his public retirement, Toshinori grappled with the loss of both his power and sense of self as he was forced to redefine himself without it.
In the aftermath of his retirement, Toshinori struggled to find his place in a world that still needed All Might. Forced to confront who he was without One For All and the future that Nighteye foresaw, he chose to live despite it.
An Encounter
An encounter with the hero-killer Stain opened Toshinori’s eyes and strengthened his resolve once more. Despite his quirkless state, he poured all the money he had earned over the years into a project that would allow him to remain a symbol, even without One For All.
Final Battle
The future foreseen by Sir Nighteye loomed ever closer, but Toshinori never went into a battle believing he would lose. As the heroes faltered and hope waned, he revealed the powered suit created for him by Melissa Shield, standing this time as Armored All Might.
All For One intended to show the world that the Symbol of Peace had finally been shattered. With a failing body and a powered suit reduced to ruin, Toshinori recognized the moment for what it was, but even then his resolve never faltered. Refusing to surrender to fear or despair, he endured until Bakugo intervened, pulling him from the Villain’s grasp. Though Toshi took no further part in the battle, he survived. As the fight continued, All For One would ultimately be defeated, along with Shigaraki.
The Aftermath
In the aftermath, Toshinori became the vice principal at UA High, remaining close to the next generation of heroes he believed in so deeply. Free from the burden of an uncertain future, he could finally stand as himself. Proud, content and surrounded by the future he had helped to secure.
