18+ Tensei Inma-ou no Harem Ikusei

Zenon Albanote, the Incubus King who stands at the very pinnacle of these demons, has reincarnated as a human in search of new "prey" (females). Over a decade has passed since then, and Zenon has already grown tired of the human women he has bedded. However, just when his boredom peaks, he receives an invitation from the Royal Lucetilia Academy of Magic, which has caught wind of his extraordinary talent.

From noble young ladies to feisty, combative girls, the most promising young females gather at the greatest academy in the human world.

(Source: Kadokawa, translated)