My Hero Academia's big spin-off Vigilantes recently ended a major arc exploring Aizawa's past. Filling in this important part of his life before becoming a pro hero, the arc saw the young Aizawa grow close with Yamada (Present Mic), Kayama (Midnight), and his best friend, Oboro Shirakumo. The friends wanted to open up a hero agency of their own after graduating U.A., but Shirakumo was tragically killed when he was caught in the havoc of a big villain'sattack. But the main series' latest string of chapters revealed that Kurogiri was actually a Nomu based on Shirakumo's base cloud quirk.