Kei Amane is one of the two female leads in the romantic comedy anime. She is a high school student and a classmate of the protagonist, Takuya Seo, where she sits in front of him alongside her close friend, Kotoko Ijichi.

In terms of background, Kei is characterized as a "white gal" or "cool beauty," a type of gyaru known for having a more refined and elegant aesthetic. Her appearance is striking, with long brown hair that reaches past her hips and blue eyes, often seen wearing the standard school uniform with a tie and vest. She is frequently mistaken for a model due to her looks and is often scouted for such work, which contributes to an initial perception of her as aloof or stuck up.

Kei’s personality is defined by a notable contrast between her public demeanor and her private interests. On the surface, she has a cool, reserved, and somewhat scatterbrained personality that makes her difficult to read. Her calm and distant nature leads others, including Takuya, to assume she lives in a different social world entirely. However, beneath this elegant exterior lies a deep and secret otaku side. She is a passionate fan of anime and games, specifically the magical girl series "Glittermon" (or "Kirarimon Pets"), which is the same niche interest that Takuya hides. This hidden fandom is a core aspect of her character.

Her primary motivation stems from this shared passion. Initially, Kei is content to keep her hobbies a secret, but her bond with Takuya grows when she inadvertently reveals her knowledge of their favorite show. Unlike the more openly energetic Kotoko, Kei’s actions are driven by a desire to connect with someone who shares her genuine enthusiasm for otaku culture without judgment. She is a "secret otaku," and the story explores her gradual process of opening up and dropping the cool facade.

In the story, Kei serves as one of the central figures who bridge the gap between the social "caste" of gyaru and outcast otaku. Alongside Kotoko, she becomes one of Takuya’s first real friends, and the three form a close-knit group that bonds over anime, games, and shared fandom. Her role is often that of the more level-headed counterpart to Kotoko’s boundless energy, though her own quirky obsession with their shared hobby frequently surfaces.

The key relationship in Kei’s life is her friendship with Kotoko Ijichi, who acts as a social anchor and helps bring Kei out of her shell. Her relationship with Takuya Seo is the other central dynamic; it begins with mutual misunderstanding and distance but develops into a genuine friendship founded on a shared secret love for "Glittermon".

Kei undergoes a notable character development as the series progresses. She starts as a figure who is hard to get a true handle on, but as she spends more time with Takuya and Kotoko, her cool demeanor softens. She shows a more flustered, shy, and sensitive side that contradicts her "stuck up" image, revealing a personality similar to a tsundere, where a tough exterior hides a more vulnerable interior. Her development is about learning to be open about what she loves.

Regarding notable abilities, beyond her surface-level talent for attracting modeling scouts due to her looks, Kei’s most significant ability is her deep, encyclopedic knowledge of her favorite anime and related merchandise. She recognizes Takuya’s limited edition eraser and understands the value of a secret figurine box, proving her fandom is not superficial. This shared expertise is the primary tool through which she connects with others.