Kokoa Hamana functions as Hanabi Ayase's principal rival for Yuuto Takao's affection, persistently utilizing deceitful and manipulative strategies in her quest to become his girlfriend, convinced Hanabi is undeserving of him.

Visually, she is a beautiful girl distinguished by large brown eyes and curly reddish-brown hair, usually secured with a thin yellow headband. She complements this with curtain bangs swept to the side, often appearing in a pink blouse and a white dress patterned with flowers.

Her personality exhibits stark duality. Kokoa presents a meticulously crafted facade of sweetness, innocence, and kindness to others. This artificial veneer masks her true, vain, selfish, and harsh nature. She harbors deep resentment towards Hanabi, actively seeking to erode her confidence and sabotage her relationship through calculated psychological manipulation and social undermining.

Her actions reveal a pattern of deliberate antagonism. She orchestrates classroom sabotage, coercing Hanabi into participating only to falsely accuse her of masterminding it when discovered. Kokoa employs performative crying to gain sympathy and turn classmates against Hanabi, though her deceptions are frequently exposed. She mocks Hanabi's physical development to provoke insecurity regarding her bond with Yuuto. Kokoa also leverages personal information, like possessing Yuuto's profile details, to taunt Hanabi and sow discord.

Her name Kokoa (心愛) combines the kanji for "heart, mind, soul" (心) and "love, affection" (愛). Her surname Hamana (浜名) translates to "beach, seashore" (浜) and "name" (名).

Throughout the series and related media, Kokoa exhibits no substantive development or redemption. She remains steadfastly entrenched as an antagonist, perpetually employing underhanded methods to disrupt Hanabi and Yuuto's relationship without achieving her objective or experiencing significant personal growth. Her interactions consistently demonstrate a cycle of manipulation, exposure, temporary setbacks, and renewed interference efforts.