A 72-hour record of having sex with my girlfriend's G-cup sister from morning till night during a family trip that lasted less than 3 days. (Aibaoling SSIS-460)

Before my girlfriend went on a trip, her younger sister came to visit. The three of them chatted about the past until late at night. The next day, after my girlfriend left, only her sister and I were at home, and she suddenly confessed her feelings to me...