: All Might’s former sidekick from his younger days in America. He is a world-renowned scientist and the inventor of All Might’s hero suits.

: The main antagonist and a leader of a group of thieves. He possesses a Metal Manipulation Quirk and is secretly aided by All For One, who provides him with a Quirk-amplifying device.

: All Might and Izuku Midoriya travel to the island for the "I-Expo" to visit All Might's old friend, David Shield . During a formal gala, a group of villains hacks the security system and takes everyone on the island hostage. Key Characters

: It allows Midoriya to harness 100% of One For All without his bones shattering.

The story is set on , a massive, man-made floating city housing over 10,000 scientists who research Quirks and hero support items. The island is governed by security systems on par with the Tartarus prison.

A significant plot element is the , a mechanical arm brace invented by Melissa Shield .

: David’s daughter and a brilliant student scientist. Like Deku once was, she is Quirkless , which allows her to bond deeply with Midoriya.