The Misfit of Demon King Academy season 2 episode 6
Episode title: The Great Mother Spirit and the Demon King's Right-Hand Man
Anos and the others have infiltrated the Underground Dungeon. Before their duel against Avos Dilheiva, they use Time Magic, Revalon, to go back in time to Gairadite two-thousand years ago, in order to unravel the secret behind Misa’s birth, Shin Reglia, Anos’ right-hand man’s, intentions, and the reason behind the Great Spirit Leno’s death. What Anos saw in the world after he had passed was―.
