After her husband gets laid off, economic hardship forces the Yamashiro couple to move back into the family home, where her father-in-law lives alone. The wife, Mizuho, grows exhausted by life with her father-in-law and turns to masturbation to relieve her stress. But one day, her father-in-law catches her in the act. Once a man who indulged in countless affairs, he still burns with unchecked desire and begins to set his sights on his daughter-in-law's youthful body. Unable to confide in her husband, Mizuho can only silently obey her father-in-law's commands. Yet he isn't satisfied—driven to expose her deepest shame, he forces her to endure humiliation in front of both of them, gradually tightening his complete control over her.