PPPD-876 Taking her boyfriend home to play, the younger sister had her lover stolen by her sister

She played for about two days. My girlfriend is an extremely cute, beautiful person and I love her very much. The only thing I don't like is that she always makes me wear a condom when having sex. Today, while preparing to "fight", her sister suddenly came home drunk. So we stopped to put her sister to bed. I couldn't sleep so I went out to drink water when suddenly her sister came close to me and thought I was her lover and started flirting with me. And our secret relationship started from there...