"Ah," "Ah," is a common scene in the home: two people going to the bathroom at the same time. "Mom, go first." "Oh, I'm sorry." The son gives his turn to his mother and casually waits outside the door. Then, in the silent hallway, the sound of urination can be heard from inside: "Shaaaaa... Trickling...". The son feels embarrassed to hear the sound of his mother urinating for the first time, but for some reason he impulsively listens and becomes excited, and realizes that sexual feelings towards his mother have begun to grow within him...