A masochist's sexual inclinations turn her interest in being tied up into desire as her body becomes immersed in pleasure! "One day, Mai witnesses her mother and stepfather having SM sex and peeks in. Seeing her mother's ecstatic expression while tied up, she feels a strange excitement and masturbates. While her mother is away, her stepfather scolds her for peeking and punishes her. This is the start of her training, and Mai falls into the role of a rope slave..."