Nana To Kaoru Vostfr [better] -

: The "perfect" girl—beautiful, top of her class, and a member of the student council. Kaoru Sugimaru

The plot is set in motion when Nana discovers a leather "breathplay" collar belonging to Kaoru. Instead of being repulsed, she asks him to perform "breathplay" on her to help alleviate her crippling anxiety. This evolves into a series of "sessions" where Kaoru dominates Nana in non-sexual (yet highly erotic) BDSM scenarios. They agree that during these sessions, Nana is merely a "slave" and Kaoru is the master, stripping away her public persona and allowing her to find mental freedom. Nana to Kaoru VOSTFR

As this was never officially licensed in English or French, most viewers access it through fan-translated versions (VOSTFR). These subtitles generally capture the technical BDSM terminology used by the author, Ryuta Amazume. Pros & Cons Anime Review: Nana to Kaoru OVA Episode 1 - matthigh : The "perfect" girl—beautiful, top of her class,