One day, Sota, a university student, is summoned to another world! Moreover, after being summoned, he was mistaken for a hero and imprisoned in the Demon King's Castle, where he was in a desperate situation...! Sota gets through the predicament with his natural skill, but for some reason he ends up solving the embarrassing problem of Fafnir, a super beautiful demi-human...!? Win the hearts of the demi-human girls living in Demon King's Castle and aim to escape from Demon King's Castle! A fantasy romantic comedy that opens up a different world with its natural business spirit, begins!