Mother-in-law Ayano was doing masturbation, which is a daily routine. Satoshi, a prosthetic breath, was sneaking a peek at the whole story. When I pretend that Satoshi is back after masturbation is over and I'm taking a break ... Ayano was in a hurry and forgot to put on her panties. Satoshi knows that Ayano is wearing no underwear, and attacks from behind.