Yuusha Party wo Oidasareta Shiryou Majutsushi wa Lich ni Natte Maougun de Daisuki na Kenkyuu Life wo Okuru

The strongest necromancer in the hero's party was thought to have lost his life in the midst of battle and was abandoned. However, he had not died. He was revived as a lich, the creature strongest in terms of both physical and magical power, and resolved to leave the human race and live on the side of the demon races. The reason was because among the demon races, he could freely research the necromantic arts in a easygoing environment! With Alice as his partner (a beauty, one of six demon generals), the lich immerses himself in his research. Will the lich really be able to live a life of research in peace and quiet without being disturbed by adventurers!?

(Source: Bunkasha, translated)