I'm sorry, but... you ladies are too beautiful!!!

Today is the first day I came to visit my girlfriend's house. She lives with her older sister, but today her sister is away on a business trip. While chatting with my girlfriend, her sister suddenly returned. It turns out that due to a misunderstanding on the partner's side, the business trip was canceled. Whether it was accidental or intentional, her sister presented her perfectly round and beautiful large buttocks in front of me while my girlfriend was making tea. That night, the image of her perfect buttocks kept appearing in my mind, keeping me from sleeping.

When I wanted to have sex, my girlfriend refused. As I was planning to go to the bathroom to relieve myself, I heard moaning coming from somewhere. Following the moans, I found that Arisu's room was open, and upon looking inside, I discovered her masturbating! I officially got to admire her beautiful large buttocks! While I was engrossed in watching, she noticed me. But instead of getting angry, she pulled me into the room, allowed me to kiss her, and we had sex! Unlike my girlfriend, she let me have sex with her whenever I wanted. From then on, we secretly continued to have sex with each other while I maintained my relationship with my girlfriend...