Kikaku Hazure no Eiyuu ni Sodaterareta, Joushiki Hazure no Mahou Kenshi
規格外れの英雄に育てられた、常識外れの魔法剣士
A young man who died saving a girl is reborn in a different world and taken in by an elderly man. The old man is not an ordinary individual but a "hero" lacking basic common sense. As the boy matures, he ends up forming a harem.