Himari Kino is a cheerful and energetic first-year high school student with a slim build and average height, often appearing slightly shorter than her peers. Her eyes shift between shades of orange, pink, and peach, and she has shoulder-length light peachy-orange hair, partially styled back into two braids tied with a ribbon and swept to the side. She typically wears a grey pinafore, white shirt, yellow and orange bow tie, white knee-length socks, and brown shoes as her school uniform. In casual settings, she favors feminine clothing like blouses, skirts, and dresses, often choosing pink.

Her personality is consistently joyous and puppy-like, earning her a reputation as an All-Loving Hero and a Nice Girl. She is kind, honest, and never speaks ill of others. Initially oblivious to romantic love, she openly expresses admiration, which is sometimes misinterpreted. Naturally friendly, she easily befriends even reserved individuals. She loves pasta and has a pet cat named Marota. A recurring visual motif depicts her with dog ears and a tail to emphasize her playful nature.

Her background places her birthday on July 18, making her a Cancer with blood type O. She is the eldest daughter in her family, which includes her parents and their cat. She has been best friends with Miki Mizuguchi since elementary school, and they now share the same high school class for the first time since seventh grade.

The plot begins when Himari sees Yori Asanagi perform with a band at the school welcome party. Enchanted by the music, she confesses to having "fallen in love," meaning it as admiration, though Yori misunderstands. Himari then discovers Yori practices guitar on the school rooftop and begins visiting her there daily. When rain prevents a meeting, she seeks Yori in her classroom and later invites her on a solo outing, where Yori confesses romantic feelings.

This confession prompts Himari to question what romantic love means, and she postpones her answer. Her confusion deepens upon learning Aki Mizuguchi also has feelings for Yori. As Yori joins the band SSGIRLS and has less free time, Himari joins the Cooking Club, befriending its president, Momoka Satomiya, and gaining a confidante.

After watching another SSGIRLS performance, Himari realizes her feelings are romantic and accepts Yori’s confession. Through Momoka, she meets rival band Laureley and its former SSGIRLS vocalist, Shiho Izumi, who left after a feud with Aki. Himari tries to help them reconcile, and Shiho appoints her as Laureley’s manager partly out of spite. Himari embraces the role, working hard to support the band while mending Aki and Shiho’s friendship, contributing to their reconciliation at the school festival.

Shiho, typically distrustful, opens up to Himari about her past, including her decision to become a professional musician to honor her late friend Kyou Amasawa. Though generally kind, Himari becomes angry when Shiho insults Yori and confronts her. Even as a manager, Himari prioritizes her relationship with Yori, asking to be kissed to grow closer as girlfriends, which sometimes sparks Yori’s jealousy. At a summer festival, worried about their relationship, Himari asks Yori to share her true feelings. After hearing Yori, Himari assures her that her singing will always be special. They promise to communicate openly and share their first kiss under the fireworks.

After the festival, she stays overnight at Yori’s house, revealing a more mischievous and tempting side. She grows bolder and more affectionate, often challenging Yori’s self-control. Her relationships remain central: she maintains her childhood friendship with Miki Mizuguchi, develops her romance with Yori Asanagi, and befriends Momoka Satomiya and Shiho Izumi. She works to repair the friendship between Aki and Shiho and supports them when they start dating.

She sings the song "Gifty," which served as the ending theme for the anime adaptation.