Kisaragi Yamaguchi functions as a primary viewpoint character, distinguished by large round glasses central to her bespectacled student identity. Her brown hair complements an innocent, approachable appearance. Personality-wise, she embodies gentleness and persistent effort despite chronic clumsiness, frequently breaking objects like her teacher's coffee mug and issuing profuse apologies. Athletic endeavors see her glasses flying off, ensuring she is typically chosen last for team sports. Naivety permeates her interactions—she misses jokes and falls for pranks, such as buying pencils falsely attributed to Sugawara no Michizane. She harbors a vivid imagination, drifting into surreal daydreams.

Raised in a Shin Buddhist household, this background dispelled childhood belief in Santa Claus. She owns two dogs adopted during elementary and middle school, contrasting her pronounced affection for cats. This feline obsession fuels her constant drawing of "suneko" (plain-colored cats), inspired when her friend Tomokane misread the kanji for "sketching" as "plain cat." Domestic skills include thrifty spending but extend to cubist-style cooking—a destructive habit originating from childhood pretend cooking games. She favors white and blue.

Within her GA-1 class, she maintains close friendships. Noda Miki and Tomokane involve her in pranks and teasing, leveraging her gullibility. Namiko Nozaki adopts a protective, motherly role, while Miyabi Oomichi ("Professor") reliably supplies items from her jacket. Kisaragi regards upperclassman Mizubuchi, a childhood friend who recommended Ayanoi Academy, as a mentor.

As an art student, she dedicates herself to painting and pastels but struggles with light sketching and fashion design. Her glasses critically affect artistic perception: without them, her vision blurs into abstraction, yet classmates occasionally praise the resulting work as superior, implying her spectacles limit creativity. She discovers an unexpected talent for accurately throwing sharpened pencils. Her studies encompass color theory fundamentals and commercial design concepts like typography.

Gradual confidence growth marks her development. Early timidity evolves into assertiveness, particularly during later group projects like festival leadership. Her artistic focus shifts from foundational techniques to art history and diverse mediums, culminating in emotional responses to upperclassmen's graduations. This progression reflects deepening investment in both her craft and school relationships.