H-cup but still developing, wearing cotton underwear but using it to seduce her girlfriend's younger sister. (MIDV-909)

She looks like a child, but has the body of an adult!! Her younger sister, Mao-chan, has an H-cup bust but is still developing. She has almost zero sex education and even wears cotton underwear. However, she's recently developed an insatiable interest in erotic things! With her limited knowledge, she uses her underwear to seduce her older sister's boyfriend! The obvious wet patches on her cotton underwear—are they adult secretions!? Overflowing with puberty hormones, driven by instinct, she experiences her first reverse sex! Wearing her first pair of sexy lingerie, she raids the place at night for sex! This makes her a naughty adult!