Villainess Level 99: I May Be the Hidden Boss But I'm Not the Demon Lord - Season 1 Episode 12 The Hidden Boss Battles the Demon Lord
Overview: At long last, Yumiella and her companions reach the Demon Lord's castle, but his power is so great that she's the only one who stands a chance against him. Then the Demon Lord tells them the true story of his connection to Valschein's royal family.