Mao Gakuin no Futekigosha - Season 2

Having led a life of warfare, death and destruction, the unbeatable Demon King Anos Voldigoad decides to leave it all behind and reincarnate into a future era, hoping it will bring him some peace and tranquility. He is reborn into a peaceful age, where magic users must attend an academy to develop their abilities. Having kept his memory and power, Anos quickly marks himself out as an exceptional student. But he senses something is amiss in this era, and decides that investigating this will be his quest, alongside his more entertaining school life.