Iris, a 10-year veteran of possession, awakens her mana but, with a pitiful talent, spends three years accumulating debt to learn magic, only to master the art of hand-washing. Eventually, her family falls into ruin, and she is reduced to a maid. As a maid, Iris gets locked in the Duke's underground library due to the mischievous antics of a young master, where she finds endlessly replenishing sandwiches, strange magic circles, and books. She’s forcibly trapped in what feels like a magic theory academy... ‘I’ll sue the young master once I get out... No, just let me out already.’