Mushoku Tensei: Jobless Reincarnation

A thirty-four-year-old shut-in, kicked out of his parents' house and run over in the same day, wakes up in the body of a newborn with all his memories intact. The world he's been dropped into has swords and lightning bolts and elves — and it doesn't give second chances to people who waste them.

Renamed Rudeus Greyrat, he takes one decision at a time: master magic before he can walk, treat the people around him properly for the first time in his life, and earn — slowly, deliberately — a place in a family that actually wants him there. The road from there reaches across a continent, two generations, and a war that the previous version of himself would never have been brave enough to face.