He has always dreamt about an SM relationship with his childhood friend and next-door neighbor Nana Chigusa, who is looked upon as perfect and is always the target of boys' eyes. Their relationship has somewhat deteriorated through the years, due to them hanging out with different people and because Kaoru is not taking his education too seriously. Nana has become very stressed at school, that a teacher suggests she find a way to relax. Nana finds the leather one-piece that Kaoru bought and tries it on but accidentally locks herself in it and doesn't have the key! After Kaoru frees her of the one-piece, Nana soon discovers that the activity has caused her to relax and improve her academic performance. Unbeknownst to both Nana and Kaoru, Sarashina and Mitsuko are, in fact, lovers and Mitsuko is the main inspiration for Sarashina's novels, but their feelings for each other seem to have become twisted and broken over the years.