OVA
Description
Kozue appears in the spin-off series "Magical Star Kanon 100%" as a supporting character. She is an elementary school student under 14 years old, characterized by her purple hair typically styled in two bushy pigtails secured with yellow ribbons featuring red stripes, and red eyes. Her wardrobe varies: she wears a one-piece dress at home, while at school or in public, her outfit consists of a dark slate blue jacket over a light steel blue dress with white edges, brown shoes, slate gray socks, an orange tie, and a white collar with red edges. She also owns a two-piece swimsuit featuring a front ribbon.

Her personality is soft-spoken, polite, and kind. She demonstrates consideration for others, organizing a sleepover with her friend Maron Nakagawa and accompanying her to the swimming pool. Kozue is a devoted fan of the idol Kanon Nakagawa but remains unaware that Maron is Kanon's transformed identity.

During a sleepover with Maron, Kozue becomes a victim of a stray runaway spirit attack. This alters her physiology, causing a temporary physical transformation that frightens and confuses her, leading her to express despair to Maron about her perceived inability to resemble Kanon anymore. She reverts to normal shortly afterward. The next day, she questions Maron about whether Maron experienced similar effects, receiving an evasive response.

At Maijima swimming pool, Kozue and Maron encounter another incident when the sky darkens due to the spirit Bell Mark Atsume. Unable to tolerate the sudden cold, Kozue trembles and falls into the pool. Kanon intervenes to resolve the situation, after which Kozue and Maron share ice cream and later discuss dinner plans.

During an event where Bell causes everyone to become incapable of lying, Kozue directly asks Kanon whether rumors about Kanon having a secret lover are true. In a subsequent major stray spirit attack, Bell identifies this spirit as the leader of the stray spirits, responsible for shrinking Kanon and stealing "dreams". The spirit attaches a line to Kozue's head, plunging her into despair as she laments her perceived inadequacies, like never growing tall and having many dislikes. Kanon communicates with Kozue mentally during the battle, urging her to stay strong. This intervention helps Kozue break free from her depressive state. She and the rest of the city then witness Kanon defeat the spirit by singing "Love Call".

Kozue's background includes winning an audition to become Kanon Nakagawa's "little sister" for a television series, a role she deeply cherishes. She remains unaware of Maron's true identity as Kanon throughout their interactions. The name "Kozue" translates to "treetop".