My sister moved in with me after saying she wanted to go up to Tokyo. She's completely indoors and has communication issues. But her breasts are plump and undeniable. They grow naturally without any effort on her part. She always dresses erratically and provocatively, making it impossible not to notice... One day, my secret of masturbating using her got out, leading to an unexpected seduction! My sexual desires exploded! "If you don't teach me how to have sex, I might get pregnant by some weird guy!" *The contents may vary depending on the recording method.