Yukino appears as the secretary of the Fuuka Student Council and Haruka Suzushiro's best friend and confidant. She is in the same class as Mai Tokiha and Yuuichi Tate. She is frequently seen with her laptop computer and occasionally runs the communications network of the Executive Council. An introvert, Yukino frequently corrects Haruka's mispronounced or misspelled words as and attempts to calm the hot-headed Haruka down during crises. Yukino has been friends with Haruka since they were small children, and was often defended by Haruka when she was unable to defend herself from bullying. As such she feels great loyalty towards Haruka and often accompanies her during her (sometimes ill-planned) attempts to protect the school.
Yukino is revealed to be one of the 12 HiME after a vampire-like Orphan sent by the SEARRS foundation begins to attack girls on campus when she is contacted by the school's headmaster Mashiro Kazahana, who warns that Haruka may become a target if the Orphan attacks continue