Tsubasa is Koyomi's classmate and the class president. Koyomi describes her as "the class president of all class presidents." She is the main character of Tsubasa Cat arc.
Prior to the novel's beginning, she was possessed by a bakeneko during Golden Week due to stress over her family. Although it has since been resolved with the help of Shinobu at a cost of her own memories, the problems emerged again right before the school festival because of different stress. Koyomi was told by her bakeneko form that she has feelings for Koyomi. In Tsubasa Tiger, on her way to school, she met a tiger that is able to talk. Her house also burns down which causes Black Hanekawa to appear, due to the stress of her house burning down, which causes Black Hanekawa to look for the tiger warning that if the tiger hurts Hanekawa, Black Hanekawa herself will kill the tiger. Though the tiger states that the problem was with Hanekawa seeing him in the first place. Tsubasa Tiger was also written in Tsubasa's perspective instead of Koyomi's.