Two years into their marriage, Shihori still loves her husband, but she feels their daily life has grown stale. One day, when he confesses his NTR fantasy, she rejects it outright. Seizing the opportunity, her husband encourages his younger brother—who has long harbored feelings for Shihori—to seduce her. He sets up hidden cameras and watches from a business trip, half-jokingly orchestrating the cuckolding. He becomes aroused seeing his wife's expression—mixed with guilt and pleasure—as another man's cock penetrates her. But as the two grow genuinely passionate and emotionally connected, he grows anxious, yet it's already too late. Within just three days, he can do nothing but watch helplessly as his wife becomes his younger brother's woman, sucking his fingers in helpless resignation.