Mušoku tensei: Isekai ittara honki dasu

Despite being bullied, scorned, and oppressed all of his life, a 34-year-old shut-in still found the resolve to attempt something heroic - only for it to end in a tragic accident. But in a twist of fate, he awakens in another world as Rudeus Greyrat, starting life again as a baby born to two loving parents. (Crunchyroll)