Ruby Hoshino is the daughter of Ai Hoshino, she is twins with her brother, Aquamarine Hoshino. Ruby has chosen to fulfill her mother's wish, to become an idol, she decided to relive the fallen idol group, B-Komachi. After the deaths of some of B-Komachi's members (Inc. Ai), they had decided to disband. Ruby had the task of turning B-Komachi into a well known group once again, but she does seem interested in finding someone as a love interest.