My mother-in-law Lily came to Tokyo from my hometown to support my wife who is nervous about giving birth. I thought that my mother-in-law's consideration would calm my wife down, but she didn't improve her mood. She even banned me from masturbating because she couldn't stand the idea of me getting pleasure on my own. I was at my wit's end with my sexual desire building up day by day, so I lied to Lily and told her it was a Japanese custom and asked her to take my wife's place. Lily was confused and embarrassed, but gradually she accepted my cock...