Mitsuru is beautiful, graceful and admired by many people, but she has a weird problem--a single, violent movement against her can get her begging sweetly for more! Her nickname M, also stands for masochistic.
Natsuhiko, is a guy who found out Mitsuru's secret on their first day of senior high school. Even so, he has an equally bad problem--the mere glimpse of his reflection can send him into a flying fit about how beautiful he is! He is nicknamed as N for narcissistic.
They both hope to minimize their chances of being exposed because of their weird behaviours.