Kaoru Sugimura (杉村薫, Sugimura Kaoru) is a 17 year-old high school student in class 3-F of Sakuramizo Academy. He lives with his mother, a single parent. He is a self-confessed virgin and his only hobby is SM (Sadomasochism), which he engages in by purchasing sex toys, rope for shibari bondage and fetish outfits that are designed to fit his next door neighbor and childhood friend, Nana Chigusa.
Kaoru gets his understanding of SM and the Dominant/submissive relationship from the writings of SM author Sarashina Taika.
He is secretly in love with his next-door neighbor Nana, whom he has known since they were kids, and becomes secretly overjoyed that Nana has agreed to participate in the S&M play. An average student, he rues the thought of eventually having to let Nana go on with her life after high school.
He constantly struggles to hold himself back, when Nana willing gives up herself for their "Breathers". Initially, he holds intensely dark desires to dominate Nana, which he holds back for a while, but eventually realizes he doesn't want to hurt her, and merely loves her and wants her to love him back. He decides to step up and begins to improve himself, in the hopes that he will be able to stand along-side Nana one day. Their relationship further develops in the spin-off, "Black Label" In the live-action film he is portrayed by Rakuto Tochihara.
Kaoru is a Sadist at heart, but also kind hearted, and sometimes doubts himself. But he makes up for this with creativity.
He is also a manipulator, and has a knack for getting others to do things for him, like getting Nana to beg to show off a S&M costume, as well as keep going with it, which he also enjoys.
- Nana -
He has always loved Nana, and she back to him, more than he knows, she has to try really hard to get it through his thick head that she isn't giving up on him.