Nana to Kaoru  

Nana and Kaoru, ナナとカオル

Kaoru is a 17-year-old virgin who has an S&M fetish. He has always dreamt about having an SM relationship with his childhood friend Nana, who he sees as the epitome of perfection and is often targeted by boys. Despite their friendship deteriorating over time due to hanging out with different people and Kaoru's lack of seriousness towards education, Kaoru's mother gives some of his S&M toys to Nana for safekeeping. One day, while trying on the leather one-piece that Kaoru bought, Nana accidentally locks herself in it and doesn't have the key. Kaoru frees her from the one-piece, but Nana realizes she may enjoy Kaoru's hobby more than she thought, leading to them engaging in "breathers" together. These breathers are meant to relieve Nana of stress caused by her efforts to maintain perfect grades and reputation.