Rio Ootori

She is the student council president and a wealthy ojousama. Her mother was a widow, who then passed away and Rio was left in care of her mother's new husband. She also doesn't have any siblings.Rio and Mamoru are childhood friends. Although they know each other's feelings, their unclear and ambiguous relationship leads them to despair. Rio finds herself involved in idol activities after accidentally participating in a beauty pageant. Mamoru is warned that Rio is a prize for “Sacrifice,” a way for the powerful and black-hearted to pass the time.