Koko-chan serves as a supporting character in the OVA "Magical Chocolate," functioning as both classmate and friend to protagonist Mami-chan. During Mami's struggle to confess her feelings to Ishida-senpai, Koko-chan reveals the rumor of a mysterious "Magical Chocolate" imbued with a love potion capable of making the recipient fall for the giver. This disclosure directly catalyzes Mami's pursuit and use of the chocolate to win Ishida-senpai's affection. Koko-chan's role remains primarily functional, supplying the pivotal information that propels the plot. The OVA's limited runtime omits exploration of her background, personality beyond friendship with Mami, or character development. No official media beyond this OVA includes her presence or role.