My girlfriend's younger sister is a gravure idol with huge K-cup breasts! She's supposed to be protecting her nipples, but she's always making mistakes at home! Because her breasts are so big, she's unintentionally flashed them multiple times. (Koikawa Momo MIDA-570)

It was my first time spending the night at my girlfriend's house, and my first time meeting her younger sister, Momo-chan. Momo-chan usually keeps her breasts flat and tightly covered when she's out, but at home, her nipples are spilling out, and she's braless, her breasts are completely exposed, full of gaps. And I also discovered that she's a gravure idol I've been secretly supporting behind my girlfriend's back…! I get so excited every time I see my girlfriend's breasts exposed!! She's wearing so little, is she doing this on purpose? Being shown up like a breast-exposed parade, I can't contain my excitement…