And, no. I’m not talking about my theory that he and Detective Tsukauchi are romantically involved. I’m talking about All Might’s origins, or more specifically, Yagi Toshinori’s origins as well as how he first met Nana Shimura.
Let’s be honest here, even with All Might’s appearances in My Hero Vigilantes, we know very little about his family life. Wait. Does Yagi have a family? They’ve never been referenced, hinted at, or acknowledged in any way. No phone calls or secret visits or confidential reveals to Deku, nothing. So, what’s up with that?
Well, we know Yagi was shown to have a high sense of morality in a flashback where he’s presumed to be middle school aged. That same flackblack may also be when Nana decided to make him her successor. But, that still doesn’t explain how Nana met Yagi in the first place. So, here’s my theory:
Yagi Toshinori lost his parents in a villain attack or due to an accident. Maybe as a contrast to Shigaraki, where no hero helped him, Nana herself was the one who saved Yagi in his time of need. From there, it’s possible she checked in on Yagi from time to time, worried about a kid left alone in the world while feeling guilty she gave up her own child for adoption in order to keep him safe.
Yagi, experiencing the pain of his past resolves himself to become a person who defeats villains in addition to inspiring society to be the best it can be. Nana learns this, realizes he can’t be a hero without a quirk and decides to train him as her successor along with the help of her sidekick (or former sidekick if enough time had passed), Gran Torino.
So, there you have it, my theory on how Yagi Toshinori’s origins. Satisfied? What? You want to know how Recovery Girl knows about One For All factors into it? Well, that’s easy: A wizard from another dimension did it. You’re welcome, fandom.
Mammoth Base Opera Castle 