Born into a wealthy family, she lost her mother at a young age. She is Riona, a girl who was raised by a single father. At the girls' school she attends, she has many friends and a special partner of hers. She lives feeling a little lonely that her busy father has just left her house.One day, her father bought a robot that she said was her "housemaid". She witnessed the act of "Forty"...?A girl who wants her affection and a robot who doesn't know her feelings. A dramatic story of gems!