!!RAPE!!
Nosaka and Kosaki both work in the fashion industry. Kosaki is the #1 in the company and specializes in men's clothing, and Nosaka works under the #2 in the company, who specializes in woman's clothing. Upon learning that he'd have to make a men's underwear line, Kosaki decides that Nosaka is going to be his underwear model, under the guise that he has a nice butt.
Holy shit the second-hand embarrassment killed me. Can't believe I got through that.