Kana Ushiku is a high school student who transitions from observing the Cheer Association to joining it. She possesses prior cheerleading experience, having performed on a community team alongside Hizume Arima during middle school. Despite being in the same grade and joining after Hizume, Kana consistently uses "sempai" due to deep-rooted admiration stemming from witnessing Hizume's athletic abilities, which originally inspired Kana to dedicate herself to the sport. Her background includes significant childhood obesity, leading to a doctor's recommendation for exercise; joining Hizume's cheer team became her motivation for physical improvement and personal inspiration.

Initially, Kana displays hostility towards the Cheer Association, particularly concerning Hizume's participation. She perceives Hizume's talents as wasted among beginners and openly criticizes the group's skill level after their soccer game performance, acting brashly and condescendingly. Her involvement shifts after she temporarily replaces Uki Sawatari during a critical prefectural basketball game. This experience prompts Kana to reassess the group and ultimately join the Cheer Association, primarily driven by her desire to support Hizume. Her membership secures the group's official club status.

Following integration, Kana gradually develops tolerance for Hizume's new friends, though her intense focus on Hizume remains defining. She exhibits pronounced physical and emotional reactions to Hizume's attention, flushing bright red, fainting, or becoming flustered when receiving compliments. Kana is exceptionally attuned to Hizume, identifying her from isolated body parts in photographs. She consistently defends Hizume's opinions and allows only Hizume the privilege of using the mispronounced name "Hanawa," which she refuses from others. She panicked when hugged by Hizume from behind.

Her backstory reveals isolation on the middle school cheer team, as Hizume's intense focus resulted in barely acknowledging teammates, later recalling them indistinctly. Kana confesses her sole reason for staying was Hizume's presence, quitting after Hizume left. This history fuels her initial reluctance towards Hizume's new friendships and her surprise and excitement when Hizume attempts a genuine connection post-reconciliation. Her birthday is November 11, and she favors spicy foods.