Gon and Killua find themselves in Japan, so they need to find a Quirk that can send them back home from this unfamiliar world. They enroll in U.A. Academy's Hero course in hopes of using its connections, but what happens when everything they need is in someone else's hands? Being powerful doesn't mean anything if they are still powerless.

Kuroko Tetsuya and Kasamatsu Yukio become step brothers, due to their parents getting married. The two learns many things about themselves and about one another as they fond of one another. Formerly known as Big Brother Kasamatsu.