My girlfriend's younger sister's precocious breasts give me a daily erection... During two weeks of summer tutoring, I secretly and boldly commit incest, avoiding my girlfriend's gaze. (Kishi Haruka CAWD-256)

My girlfriend's family is naturist, so she's always completely naked at home. Around this time, her younger sister, Yao, who was attending tutoring classes, was staying with us for two weeks. After saying goodbye, the naked Yao started seducing me…