You are reading The Underworld Transcendent Is Unrivaled at the School! Chapter 57. Leon Klein was a hero who saved the world by defeating the Demon KingHowever, due to the kingdom's betrayal he was sent into a prison in the abyss."Secret Quest" --In a hell with no exit, a trial that will not end until one million magical beasts are defeated.After 10 years, Leon acquired the [Dark