One day, while I was living with my girlfriend, her older sister, Fua, came to stay with us for seven days. She was tall with long limbs and cute, but mature, and nothing like her younger sister... she was incredibly receptive to me and we ended up having sex. Our affair burned with guilt. We hid from her so she wouldn't find out, but we gradually became more and more bold as we indulged in pleasure for seven days.