He may look like nothing but a country boy, but Chrono Alcon is actually one of the most powerful demons the world has ever seen! All he's interested in is attending school like any other kid, but when the Demon King finds out about Chrono's power, he'll have to spend his days studying, and his nights in the dungeons, fighting monsters...?! The hit fantasy adventure manga comes to print, perfect for fans of Goblin Slayer, The Rising of the Shield Hero, and That Time I Got Reincarnated as a Slime!The twin heavenly dragons, Mithra and Alia, have been enjoying themselves immensely in the brief time they've been in Chrono’s class. However, their fun times as as students in the Demon King’s Castle is nearing an end as they must fulfill a contract that requires them to conquer a supremely difficult dungeon. Despite wielding extraordinary power as heavenly dragons, the twins seemingly have no chance of conquering the dungeon until Chrono and his classmates offer a helping hand. Will a group effort be enough to overcome a dungeon that crushed two heavenly dragons?