35-year-old Kosuke works as a sales representative for a plumbing company. His wife, Yuko, is also 35, and they've been married for five years with no children yet. One day, he witnesses his wife willingly taking an older man's cock right before his eyes—an experience so shocking it sends chills down his spine and makes every hair on his body stand on end. Amidst the confusion, his own cock becomes so hard that it ejaculates at the slightest touch. The story deeply explores his inner turmoil and the painful conflict between his emotions and reality.