Rei Shironouchi is a maid residing in the mansion with the landlady and other maids. She participates in the protagonist's pursuit of forming a harem among the household members. Rei engages in the sexual dynamics where encounters between the protagonist and one maid frequently lead to another observing, creating a chain reaction of interactions among the women. This dynamic fosters an ambiguous power balance, leaving it unclear whether the protagonist manipulates the women or they use him for their own gratification.