Komari Koshigaya occupies the middle position in the Koshigaya family, flanked by her older brother Suguru and younger sister Natsumi. She attends Asahigaoka Branch School as a second-year middle school student, serving as the eldest girl within their compact, multi-grade classroom. Her physical presence is distinguished by a notably petite frame, standing approximately 130-135 cm tall despite her frequent insistence on 140 cm. She possesses waist-length brown hair typically worn loose with face-framing bangs, emerald green eyes, and an occasional visible fang. Her attire leans toward youthful designs, partly due to her mother delaying clothing replacements until Komari outgrows them, leading to outdated items like her school swimsuit. Komari's personality revolves around an earnest aspiration to project maturity and adulthood, sharply contrasting her easily startled and superstitious tendencies. Academically diligent, she routinely falls prey to Natsumi's pranks targeting her supernatural fears—a dynamic defining their sibling relationship where irritation blends with protectiveness. She nurses profound insecurity over her height and physical development, fueling intense envy toward fifth grader Hotaru Ichijō, whose stature and composure radiate greater maturity. Within her family, Komari maintains a standard bond with the taciturn Suguru, while her rapport with Natsumi weaves teasing with mutual care. She respects her mother Yukiko yet fears her wrath. Komari's growth surfaces through gradual acceptance that seeking aid reinforces rather than diminishes maturity, exemplified when learning curry preparation under Yukiko's guidance after failures like scorched bento. Her friendships unveil complexity: she tolerates but resents Renge Miyauchi’s "Koma-chan" nickname despite their authentic connection. Her bond with Hotaru intertwines admiration for the younger girl’s poise and delight in being called "Senpai" with bitter envy over Hotaru’s physical traits. This jealousy coexists with genuine warmth, as Komari treasures their shared moments and confides in Hotaru during personal struggles, like mending her cherished plush bear Shokichi-san. Across her journey, Komari refines culinary abilities and shifts toward collaborative efforts over solitary ones to affirm her maturity. Later narratives, including the manga spin-off *Non Non Biyori: Remember*, hint at her high school transition without detailing specific experiences. Additional traits include a distaste for natto, UV sensitivity (manga-only), and cat-like eye shapes during deception or disappointment.