Riko (Ruka Kanae) and her husband Shinichi live a peaceful, ordinary life. When Shinichi's old friend Ichijo starts a house cleaning business, they reluctantly hire him. Captivated by Riko's charm, Ichijo breaks into their home while Shinichi is away on a business trip. Through his twisted training, Riko's latent masochism awakens and she becomes addicted to the pleasure. Exploiting her husband's absence, Ichijo draws her deeper into a world of forbidden indulgence. Her body, now awakened to the ecstasy of domination, grows dependent on the master's absence. Torn between guilt over betraying her husband and the overwhelming urge for pleasure, Riko gradually begins craving the training itself.