Yukimura is a member of the Neighbor's Club from Haganai
He is similar in appearance to that of a girl's, and because of that his classmates treat him differently, which Yukimura interprets as bullying. Later in the series, a turning point for Yukimura's trap life occurs. The neighbours' club visit a public bath, and Kodaka Hasegawa and Yukimura head into the men's section along with Maria Takayama, as she doesn't like the way the girls smell like vomit. He proceeds to lift up Kodaka's towel and proclaim "so this is what a penis looks like!" He asks why he has one and Kodaka explains that all guys have one. Maria then laughs because Yukimura supposedly 'doesn't have one', which makes him 'weird'. Yukimura explains that this is because he is 'too young to have one yet' and that he will get one when he is older. Kodaka becomes extremely confused, and when they reunite with the girls, Rika Shiguma helps Kodaka to reveal that Yukimura is technically a girl. Kodaka is relieved, as he was always getting embarrassed whenever he was close to Yukimura, often having to calm himself by convincing himself that Yukimura is 'just a dude'.
Reason for Cross-Dressing
Despite identifying as a boy, Yukimura dresses in girls clothes, typically that of a French maid, due to believing Yozora Mikazuki that a true man's "manliness" would show regardless of what clothes are worn.