Demon King Anos Voldigoad had been fighting a war against humanity for two thousand years; in an attempt to create peace he sacrifices his own life. Another two thousand years pass and then he is reincarnated. It is a more peaceful time but not everything has improved; demon royalty now dominates hybrids, so-called misfits of which Anos in now one. He also learns that their magical power has decreased significantly. He attends Demon King Academy as a misfit but quickly realises he is far more powerful than anybody else. Here he makes friends and works to prove he really is the reincarnation of Anos Voldigoad.
This anime series isn't that different from many others, with its hero who is clearly far more powerful than those who wish to defeat him... that said it is still a lot of fun. There is plenty of action which is fun even if the ultimate outcome is of no real doubt. Anos is a solid protagonist and the supporting characters, who join his group, are also fun to watch. The character designs are good as is the animation. Overall I'd say that while this isn't the most original series it is worth watching if you are a fan of the genre.
These comments are based on watching the series in Japanese with English subtitles.