The Misfit of Demon King Academy
魔王学院の不適合者 ~史上最強の魔王の始祖、転生して子孫たちの学校へ通う~, Maou Gakuin no Futekigousha: Shijou Saikyou no Maou no Shiso, Tensei shite Shison-tachi no Gakkou e, The Misfit of Demon King Academy: History's Strongest Demon King Reincarnates and Goes to School with His Descendants, Maou Gakuin no Futekigousha
After 2000 years has passed, the ruthless demon lord has just been reincarnated! But his aptitude at an academy for nurturing candidates for demon lords is, “inept”!? Having the capability to destroy humans, elementals, and gods, after a long period of countless wars and strife, Arnos the demon lord became sick and tired of all that and longed for a peaceful world, so he decided to reincarnate to the future. However, what awaited him after his reincarnation is a world too used to peace that his descendants became too weak due to a huge weakening in magical powers.