HBAD-701 - Thought my friend's sister was shy, but she turned out to be a big-breasted nympho who loves it

Kenji often drinks at his colleague Hiroshi's house. One day, he peeks at Hiroshi's plain-looking sister, Kaichi, in the bath and discovers her erotic, huge breasts. Seizing the moment while Hiroshi is away, Kenji makes his move. To his surprise, Kaichi is completely submissive and incredibly sensitive, leading to an unrestrained session of pure pleasure.