Katsura Yukiji is the sister of Hinagiku. She is a world history teacher at Hakuō Academy and doubles as a 24-hour gate guard. She refuses to let Hayate enter the school when they first meet because she is afraid that letting unauthorized personnel on campus will result in a salary deduction for her. Her attitude softens after Hayate first saves her from falling off the clock tower, but she still almost causes Hayate to be rejected from Hakuō by unnecessarily making him anxious during his entrance exam. She repays Hayate by telling everyone in her class on Hayate's first day that he is a super cool person. She has a group of underachieving students (Izumi, Miki, and Risa) who hang out with her a lot. She lives on the Hakuō campus; she tells Hayate that she does this so that she can save rent money and use that money to buy alcohol instead.