A gamer is magically summoned into a parallel universe, where he is chosen as one of four heroes destined to save the world from its prophesied doom.

Together with her humanoid friend Reg, a young girl named Riko hopes to one day solve the mysteries surrounding the endless chasm known as the Abyss.

Aoi is startled to see her sister’s ex-boyfriend, who’s somehow still the same bright-eyed kid he was 13 years ago, before tragedy tore them apart.