A group of youths aspiring to become professional superheroes, fight in a world full of people with abilities, also known as quirks. Deku and his fellow classmates from Hero Academy face Nine, the strongest villain yet.

Class 1-A visits Nabu Island where they finally get to do some real hero work. The place is so peaceful that it's more like a vacation ... until they're attacked by a villain with an unfathomable Quirk! His power is eerily familiar, and it looks like Shigaraki had a hand in the plan. But with All Might retired and citizens' lives on the line, there's no time for questions. Deku and his friends are the next generation of heroes, and they're the island's only hope.

A mysterious group called Humarize strongly believes in the Quirk Singularity Doomsday theory which states that when quirks get mixed further in with future generations, that power will bring forth the end of humanity. In order to save everyone, the Pro-Heroes around the world ask UA Academy heroes-in-training to assist them and form a world-classic selected hero team. It is up to the heroes to save the world and the future of heroes in what is the most dangerous crisis to take place yet in My Hero Academia.