Koro Sensei Quest! Episode 11: It`s Not a Job, It`s a Calling
Episode 11 of 12 of Koro Sensei Quest!, aired March 2, 2017, 10 minutes. Available with English subtitles and dub where released.
Episode summary
When Koro-sensei was a human, he was thought of as a hero, but became bored of his work. He was assigned by Aguri Yukimura to be a Demon King and live in a castle, since his predecessor (actually Neuro from Neuro: Supernatural Detective) retired from his position.