WARNING: The following contains spoilers for My Hero Academia #304, by Kohei Horikoshi, Caleb Cook, and John Hunt, released Sunday, Mar. 7 in English by Viz Media.
My Hero Academia Chapter #304 finally returns focus to Izuku Midoriya after a long cliffhanger with his fate left uncertain. While he lies comatose in Central Hospital, Izuku's consciousness is actually elsewhere, speaking with One For All's vestiges. In the aftermath of All For One's devastating attack on hero society, One For All's previous wielders have shocking revelations to share with him that up the stakes to world-changing levels.
The fourth wielder of One For All, Hikage Shinomori, starts the chapter by introducing himself and asking if Izuku is aware of how he died. Though Izuku knows Hikage passed away when he was 40 years old, he's unsure how exactly that happened since All Might kept it from him. Hikage – overriding All Might's wish to keep this information secret – reveals that he died of old age. At the time, he says, he didn't understand why he was dying, but thanks to All Might's recent investigations, the vestiges learned through their connection to him the reason Hikage's life was cut short.
Hikage reveals to Izuku that someone with a Quirk cannot safely wield One For All. He says he died of old age, but it's more accurate to say that the cause of death was One For All. Possessing the Quirk Danger Sense in tandem with One For All ate away at his very life. As the first wielder, All For One's younger brother, puts it, "A vessel with an existing Quirk of its own could not receive One For All without warping and spilling over ... and attempting to force it anyway resulted in a shortened lifespan."
The overwhelming power of One For All has only gotten to become more deleterious since Hikage's time. All Might spent 40 years strengthening the Quirk – twice as long as any previous wielder – making it truly his own. As a result, it is now too much for even a Quirkless person to safely use. This information also explains why All Might had no trouble adjusting to One For All when he first received it: the Quirk was half as strong as it is now. However, this disturbing fact means that if Izuku passes One For All on to someone with a Quirk, they would likely have less than nine years to live, only half of the time that Hikage spent with the Quirk.
These revelations lead to the heaviest one of the chapter: Izuku might be One For All's final wielder. Every generation, fewer people are born Quirkless. They are so scarce now that Izuku was one of the few kids his age who didn't have a Quirk. By the time he'd be ready to pass down the torch to the next generation, he'd have to scour the entire world to find someone capable, let alone worthy, of wielding One For All. While the Quirk gives its users a massive power boost, every victory is a Pyrrhic one, making it as much a curse as it is a blessing.
If Izuku is the last wielder of One for All, it's up to him to end All For One's reign of terror for good. He cannot rely on a successor to shoulder his burdens like Hikage Shinomori, Nana Shimura, and All Might did before him. Failure isn't an option: if All For One and his successor, Tomura Shigaraki, aren't permanently dealt with in time, the world will lose its best hope to counter the rise of evil.
