The Misfit of Demon King Academy II

After 2,000 years of endless wars and turmoil, the demon king Anos Voldigoad struck a contract with the human hero Kanon to sacrifice his own life in order for peace to blossom. Upon reincarnating 2,000 years later, Anos discovers that the society favours his pureblood descendants over the demons that interbred with other species, such as humans and spirits, and that royal demons now severely rule over lower class hybrid demons. Anos, who is technically a hybrid now, discovers that magic in general has started to decline and that the peace he established has made his descendants weaker. Anos decides to reclaim his former title of Demon King, but first he must pass the Demon King Academy, where he is branded a complete outcast.