From MangaHelpers:
Ryouko is a pretty prudish young teenager, who doesn't even like romantic dramas on tv. One day after school, Ryouko sees her friend Miki crying while an attractive young teacher has sex with her. Instead of helping Miki, Ryouko feels frozen to the spot. Eventually, seeing Miki like that spurs her to seek out a sexual experience of her own with a boy who asks her out. Unfortunately, her tentative steps towards exploring sex quickly spiral into a nightmare. In the meantime, Miki can't figure out how to handle her own sexuality. While it may not have started out as consensual, her body enjoys sex with her teacher, and she can't help coming back for more. She can't figure out whether she really wants him or a nice boy her own age. Unfortunately for her, the adult man who is taking advantage of her sees her as nothing more than a sex toy. Will these two young girls find a way to navigate the dangerous and confusing world of sex?