Hayase Yuuka is a second year high school student. She's the treasurer of the Seminar, the student council of Millenium Science School. She oversees the school's entire budget. She's also a prominent math genius with a special talent for the abacus. Yuuka is a polite girl who likes to act very professional. As treasurer, she supervises other clubs, which leads to conflicts because of her strict approach to money. However, she is easily frustrated when dealing with unreasonable people, which often leads to angry outbursts; this has earned her a reputation for being cold and ruthless. Yuuka takes pride in her mathematical skills, to the point where she relentlessly tries to cover up her own mistakes. When she is upset, she calms herself by counting in her head. Yuuka has taken it upon herself to keep track of Sensei's spending to prevent them from wasting money on figurines and video games, often lecturing Sensei and getting annoyed at their bad habits. Yuuka really likes Sensei, but pretends not to. In the end, she always finds it hard to refuse their requests. Yuuka is 16 years old and 156 cm tall, with bright blue eyes and long purple hair that reaches down to her waist, along with braids that are tied together with triangular hairpins. She wears the standard Millenium uniform, consisting of a black blazer, a white shirt underneath, a blue tie, and a black pleated skirt. She also wears a white hoodie, black gloves and black boots. In addition, Yuuka wears a large white belt with bullet pouches attached to it. Like other students, she has a halo over her head, which is a black circle with a blue line in the middle. Yuuka carries a pair of black SIG-Sauer MPX submachine guns, which she has nicknamed "Logic & Reason". Both guns are stamped with the Millenium insignia. Yuuka's Momochat status message is "Just as I calculated...". Her birthday is March 14th. She is ambidextrous.