Vigilantes strips away the All Might mythology and asks what heroism looks like when you're not chosen, when the system has already decided you don't matter. Koichi, Pop Step, and Knuckleduster aren't fighting for glory or a hero license; they're filling the cracks the official heroes ignore, and every small win feels heavier because there's no safety net underneath it. This is what the main series only whispers about: the people who save you before the pros ever show up.

Kouichi Haimawari is a college student who once dreamed of becoming a hero, even though his Quirk only lets him slide along at roughly the speed of a bicycle. In a world where most people have powers, only a chosen few are licensed as heroes, so he fills his days with small local jobs that fall outside the reach of police and professionals. A chance meeting with Knuckleduster, a rough-and-tumble vigilante, and Pop☆Step, a popular online figure, draws him into vigilante work. When a dangerous drug starts boosting Quirks and turning ordinary people into villains, the mismatched trio sets out to stop it from spreading. Along the way they go after wrongdoers the law overlooks.