Mayu Miyano, a shy and clumsy childhood friend and neighbor of Takashi Kosuda, uses cooking as her primary means of emotional expression. With her glasses and prominent bust, she becomes an inadvertent romantic rival to Yamada, whose jealousy fixates on Mayu’s physical traits and shared history with Kosuda. Though harboring long-standing feelings for him, her reserved demeanor and self-doubt keep her from direct confession, leaving her to subtly signal affection through gestures like preparing meals.

Her innocence and perceived naivety in romance are emphasized through interactions with Kosuda, who views her as wholly inexperienced. Despite her passive role, Yamada’s envy amplifies tension in scenarios highlighting Mayu’s physicality or closeness to Kosuda.

Her arc culminates in accepting Kosuda’s relationship with Yamada and pursuing independence by attending college in another town. An unresolved subplot introduces a secret admirer who follows her there, unbeknownst to her. This transition underscores her gradual shift from reliance on Kosuda to self-sufficiency.

Symbolically linked to a magical-girl "Eros Deity," she receives advice steeped in innocent romantic ideals, such as indirect affection tactics. This contrasts with the overtly sexual guidance given to others, reinforcing her characterization as inherently artless in matters of love and desire.