In the universe of My Hero Academia, it is not necessary for everyone to possess a license in order to combat injustice. Superpowers have transformed traditional evil into something extraordinary. Trained and licensed heroes are responsible for safeguarding and defending society against supervillains. However, there are individuals who possess powers but do not have official licenses who still strive to serve the public without legal authorization. These individuals are referred to as vigilantes.
Koichi Haimawari was unable to qualify as an official hero, so he utilizes his modest Quirk to perform good deeds in his free time. One day, he encounters some local thugs and subsequently teams up with two other unlikely heroes who lack experience in fighting evil. Despite their lack of expertise, they possess the courage, or perhaps foolishness, to attempt to make a difference. However, they soon discover that combating evil requires more than just bravery.