I Got a Cheat Skill in Another World and Became Unrivaled in the Real World, Too, Vol. 1 (manga) [Paperback]

Yuuya has always been a loser, and after the death of his grandpa (the only person hehad in his corner), hes sure theres no point even trying anymore. But when Yuuya moves into his late grampss home, he inherits...a two-way door to another world?! Access to this new realm might be just the cheat Yuuya needs to succeed in his everyday life!