That is the stories that are mentioned in the manga are other people having on night stands not the manga's story and tells that having sex in a bathroom is unusual to normal one night stand stories/rumors heard by people(in the manga) plus the summary is the ukes perspective so try reading it again and see if you understand it (=・ω・=)
nope theres more chapters of this couple!
I see. Thanks. I didn't understand it well that's why I ask. English not my native language ^^"
This is just a one-shot right? 'cos in the summary it says: "There are many stories of one-night stands"