Marry the older sister, get the younger sister

My wife and I went to my parents-in-law's house for a week. It's been a while since I last saw Rio's sister-in-law, and I'm still fascinated by her beauty. One day, Rio went drinking with his friends, but because he was drunk, his wife asked me to pick him up.

Rio was afraid of being scolded by his parents so he wanted me to take him to the hotel. Looking at my beautiful sister-in-law right in front of me made me unable to control the beast inside me and did something unforgivable...