I Got a Cheat Skill in Another World and Became Unrivaled in The Real World, Too

異世界でチート能力を手にした俺は、現実世界をも無双する ～レベルアップは人生を変えた～

Synopsis

All his life, Yuuya has been bullied at school and neglected by his parents. After moving into his late grandfather’s home, he discovers a strange door that seems to be calling out to him. Yuuya opens the door, steps inside, and is suddenly transported to a magical world! This new world holds rare treasures and grants him powerful skills, which he takes back to Earth for a new lease on life. (Source: Crunchyroll)