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-class selected hero team. It’s 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.

Hana, Hinata, Noa, Koyori, and Kanon are always good friends. Today, they are having a friendly sweets party at home with Miyako's homemade sweets! The flower-shaped cookies look just like the hair ornaments worn by Hana. The hair ornament was a precious treasure that Hana received from her grandmother when she was little, and everyone was intrigued by the story. And as "practice for the school trip," they decide to go visit Hana's grandmother's house...! The "first" outing for everyone is about to begin.

The story takes place within Neo Tokyo in the year 2025, five years after a severe terrorist attack at the 2020 Tokyo Olympics. Students possessing special abilities are forced into serving an elite anti-terrorist unit created by the United Nations, fighting against threats including other ability users. If these agents fail their mission, they will be killed along with their families, who have bombs planted within their heads. One member of this covert ops unit, a Swedish girl by the name of Anthea Kallenberg, seeks to find who she really is.