My wife and I went back to my wife's parents' house for the first time in a long time. My parents-in-law welcomed us warmly. During a family get-together, my father-in-law said that he wanted to see his grandchild, and my wife suddenly got up in a bad mood. I told my parents-in-law, who were confused, that my wife was refusing to have sex at night, and that even if they asked her, it would be no use. I felt sorry for my parents-in-law's disappointment. I woke up in the middle of the night to go to the bathroom, and stopped at the light leaking out in front of my parents-in-law's bedroom. I peeked in and saw my parents-in-law having sex. I knew I shouldn't look, but I was sexually hungry and couldn't take my eyes off them. My erection wouldn't go away, so I hid and masturbated, and my mother-in-law came in. She told me to wait as I hurriedly hid, saying, "You're going to get pent up because your daughter hasn't done it, right? If it's okay if I do it," and started stroking my son. It had been a while since I had been touched, so I got excited right away, but my mother-in-law's handjob and oral sex were so sticky and skillful that it seemed as if she would not let me ejaculate, and at the moment when I was on the verge of exploding, she took it in her mouth... The next day, my father-in-law and my wife went out to a nearby izakaya. My mother-in-law must have been feeling awkward because of what happened last night... And, it was getting late into the night, but my father-in-law and his wife had not returned. I made up my mind and headed to my mother-in-law's bedroom. I gently lifted the futon of my mother-in-law, who was snoring, and caressed her. Soon, my mother-in-law's private parts began to make a squelching sound. My mother-in-law woke up in surprise. I could no longer hold back, and inserted myself into my mother-in-law half-attacking her... In reality, it was wrong... Both my mother-in-law and I knew that... but I still couldn't suppress my urge... "We're so stupid..." my mother-in-law said, smiling gently...