Necklace | Mushoku Tensei

An unnamed 34-year-old Japanese NEET is evicted from his home following his parents' death. Upon some self-introspection, he concludes that his life was ultimately pointless. Walking down a street he intercepts a speeding truck heading towards a group of teenagers, in an attempt to do something meaningful for once in his life he manages to pull one of them out of harm's way before getting himself in the way of the truck and dying. Awakening in a baby's body, he realizes he has been reincarnated in a world of sword and sorcery. He resolves to become successful in his new life, discarding his past identity for his new life as Rudeus Greyrat. Due to inherited affinity and early training, Rudeus becomes highly skilled at magic with help from his previous life's intuitions. During his childhood, he becomes a student of a demon magician Roxy Migurdia, a friend to half-elf Sylphiette, and a tutor to noble heiress Eris Boreas Greyrat. Rudeus tries his best to live this new life with no regrets to leave behind. (from Fandom Mushoku Tensei Wiki)