Koichi Haimawari is a young man with a modest Quirk who has always dreamed of becoming a hero without ever following the official path. Even so, he quietly uses his abilities to help people in his neighborhood until he meets Knuckleduster, an underground vigilante who fights criminals outside the legal system. Alongside Pop Step, Koichi becomes involved in increasingly dangerous cases connected to illegal Quirk use, drugs, and criminal networks. Gradually, he discovers another side of hero society, where some choose to act without a license when the institutions are no longer enough.