The eldest Niihara sister, a former delinquent who now works at a live house. She is the de facto head of the household in her parents' absence, ruling through brute force and intimidation, often physically abusing her younger brother.

A tall, athletic woman with a voluptuous figure, characterized by large, firm breasts and a plump posterior. She has a rough, punkish style, and her voice is loud and aggressive.

Domineering, violent, and emotionally volatile. She uses physical force to solve problems and is pathologically incapable of showing vulnerability. Her core flaw is her simple-minded reliance on power to maintain control. Under hypnosis, this is exploited to awaken a deep-seated masochism, where pain and humiliation are converted into intense pleasure, making her a perfect but challenging subject for subjugation.

Her past as a feared gang leader, where she established her identity through violence and intimidation. The first time Daiki successfully hypnotizes her, causing her to be completely unaware of his actions while he masturbates using her hair. Her deep, albeit unspoken, regret and resentment for her own violent nature, which is the bedrock of her fragile pride that Daiki ultimately shatters.

The middle Niihara sister, a university student and campus celebrity known for winning a beauty pageant. She maintains a popular, gentle public persona but is revealed to be a manipulative, sadistic tyrant at home, using her wit to torment Daiki.

An idol-like beauty with long hair, a slender figure, and notably large breasts. She presents herself with a flawless, charming exterior.

A "communication monster" who is socially adept and calculating. Privately, she is a narcissist who finds amusement in psychological torment. She is more cunning and perceptive than her older sister, which makes her a more dangerous adversary. Her core flaw is her arrogance; she underestimates others, believing she can outmaneuver anyone, which leads to her eventual defeat. Her sensitivity to pleasure is exploited to create a deep, obsessive dependency on Daiki.

Her victory in the school festival beauty pageant, which cemented her inflated self-image and sense of superiority. The moment she steals the hypnosis tablet from Daiki, marking her bid for control and her fall from grace. Her deepest attachment is to her own image of control and superiority, which is irrevocably shattered when she is reduced to a willing, pregnant sex slave, craving Daiki's validation.