Yuuya Tenjou is a boy who's been bullied all his life, mocked by everyone, even his own family. Everything changes the day he inherits his grandfather's house and discovers a secret door that takes him straight to a fantasy world. In this new world, Yuuya finds legendary weapons, defeats powerful monsters, and gains incredible abilities that completely transform his body. The best part is that he can move from one world to the other while retaining all his new abilities. Thus, from an insecure and mistreated boy, he finds himself becoming an unbeatable hero in the fantasy realm and the most popular, cool, and talented guy in real life.