Every 100 days, Gunjun breaks up with his boyfriend because he's disappointed in their relationship.
However, there is one belief that he holds fast to, and that is that every relationship has stages!
"The way I see it, you go from 1 to 10, and when you reach 100 days, you have sex!"
The opposite of this is Jung-seok, a long-haired senior who seems very light-hearted but is well-liked by people.
After getting to know him, Geon-joon simply defines him as an "asshole senior"
Meanwhile, after 100 days with his boyfriend, Gun-joon is half sad, half excited, and ends up breaking up with him for the same reason.
Feeling sorry for himself, Gun-joon has a one-night stand, and the alcohol breaks him down with an unfamiliar pain he's never felt before.
He comes face to face with a smirking man "Wait, is he...?"