From Assassins To Heroes [MHA x Assassination Classroom]

After class 3-E assassinated their teacher Kora-sensei and they received their reward money three students disappeared, Karma Akabane, Nagisa Shiota, and Kaede Kayano.

When the trio wakes up, they find themselves in a new world. It appears that they are in a world where superpowers called quirks are the norm. That's not all either it appears that they have quirks as well and they are 11 years old. Nagisa's becomes a girl and has snakes for hair, and he can turn people into stone and turn them back by touching them. Kayano has tentacles for hair that change color depending on her mood, and Karma has the ability to summon any kind of weapon.

They aren't the only ones either.