Utaha Kasumigaoka is a third-year student at Toyogasaki High School, renowned as its top academic performer and admired by peers for her beauty and intelligence. She secretly writes bestselling light novels under the pen name Utako Kasumi, with her debut "Koisuru Metronome" exceeding 500,000 copies sold through Fujikawa Fantastic Bunko. She possesses a tall, slim figure at 168 cm, with long dark hair typically featuring a white hairband. Her brown eyes in the light novel adaptations appear scarlet red in the anime; her measurements are B89/W61/H88. Outwardly calm yet sharply sarcastic, particularly within Tomoya Aki's circle, Utaha displays a disdainful exterior. Private moments reveal vulnerability, such as when accepting compliments. Though self-centered, she shows respect towards her parents, reflecting disciplined upbringing. Her intense work ethic drives her to complete writing projects overnight, demanding perfection in creative endeavors. Utaha used writing to process unexpressed emotions. She first met Tomoya at her novel's autograph event, where he became an ardent fan. Inspired by his feedback, she tailored subsequent works to his preferences, developing romantic feelings. An indirect confession via manuscript backfired when Tomoya, prioritizing fandom boundaries, refused to read it pre-publication. Hurt, she distanced herself for three months and coined his mocking nickname "Rinri-kun" (Ethics-kun). Joining Tomoya's doujin circle, Blessing Software, as its scenario writer, Utaha's interactions grew provocative: teasing Tomoya with physical proximity, initiating footsie during meetings, twice sharing his bed, and stealing his first kiss. Despite these advances, she struggled to confess directly, earning the label "coward" from rival Eriri Sawamura. She openly resented Megumi Katō for receiving Tomoya's attention, once striking her over a minor mistake during a ritual. After graduating, Utaha left Blessing Software alongside Eriri to develop the game "Fields Chronicle" under producer Akane Kosaka. She concealed her true reason for leaving—emotional distance from Tomoya—though he continued supporting her. She responded by kissing him again, resolving not to abandon her feelings entirely. During "Fields Chronicle" development crises, Utaha and Eriri enlisted Tomoya's help to delay deadlines. Utaha later contributed to Blessing Software's final game, assisting despite acknowledging Tomoya's romantic commitment to Megumi. A post-credits scene ten years later shows her as a writer for Tomoya and Megumi's company. At their wedding, she drunkenly recounted an imaginary marriage to Tomoya, causing embarrassment yet underscoring her unresolved attachment. The spin-off manga "Koisuru Metronome" reimagines Utaha as the central heroine, removing Megumi and minimizing Eriri. Here, she interacts with Tomoya as her editor, exhibiting amplified yandere traits with illustrator Mayu Sagara as a new rival. This version concludes with her romantic success, contrasting the main storyline.