Izuku "Deku'' Midoriya and his fellow students in Class 1-A of UA High's hero course have been chosen to participate in a safety program on Nabu Island. To further improve their skills and gain experience in more ordinary heroics, the students aid the kind citizens with small services and everyday chores. With the low crime rate in the quiet community, all seems well and good, but the rise of a new villain threatens to put the students' courage to the test and challenge their capabilities as heroes.
A merciless villain by the name of Nine is in search of a certain "quirk" needed to fulfill his diabolical plan—creating a society where only those with the strongest quirks reign supreme. As his attack on Nabu Island endangers the lives of the residents, securing the citizens becomes the first priority for Class 1-A; defeating Nine along with his wicked accomplices is also imperative. A straightforward strategy is formulated until a young boy named Katsuma Shimano, whom Deku had befriended, suddenly requires particular protection. Concerned for the boy's wellbeing, Deku and his classmates must now devise a plan to ensure Katsuma's safety at all costs.