Elf Tensei Kara no Cheat Kenkokuki

A genius magician created a spell that allows him to reincarnate, while keeping his memories intact. He repeats this reincarnation process 31 times, and now he has become Cyril, a elf boy living in a small village. However, the village is ruled by humans, and the elves are oppressed cruelly. In order to save his childhood friend Lucie, the reborn wizard will stand up to create a new nation where all races can coexist!

(Source: Futabanet, translated)