Kozue Takanashi, the third eldest in the Takanashi family, embodies a complex mix of warmth and profound loneliness stemming from childhood neglect. Her mother, Shizuka Takanashi, habitually overlooked her as a middle child, forgetting her name and prioritizing siblings, cementing Kozue’s enduring craving for validation. This void fuels a pattern of fleeting romantic pursuits and subsequent rejections, driving her to self-medicate with alcohol to numb depressive spirals. Though outwardly vivacious, her clinginess and alcoholism strain relationships, particularly with younger brother Souta, whom she leans on for emotional anchoring.

Employed as a self-defense instructor, Kozue displays surprising martial prowess and agility, countering her personal chaos with professional discipline. Her gymnastic finesse surfaces in erratic moments, such as scaling and perching on lampposts mid-depression. Yet domestic responsibility eludes her; she depends on Souta for household tasks and emotional stability.

Her dynamic with Souta intertwines dependency and mischief. Childhood poverty forced him into hand-me-down girls’ clothing from his sisters, including Kozue—a source of lingering shame for him. She nostalgically resurrects this past, taunting him with old photos and demanding hugs he evades. Beneath their bickering lies mutual care, evidenced by her childhood gift of a rabbit plushie he still treasures.

Kozue’s romantic journey pivots on Youhei Mashiba, whose earnest compliment during a low moment sparks her affection. Initial rejection—rooted in Youhei’s financial insecurities—gives way to gradual commitment, culminating in implied cohabitation. Simultaneously, she forges a bond with Youhei’s sister, Mitsuki Mashiba, united by shared solitude. Their friendship anchors Kozue within the Mashiba household, offering a surrogate family she frequently visits.

At Wagnaria, Kozue’s drunken intrusions and unpredictable visits initially ruffle coworkers. Yet her authentic devotion to Souta and growing self-awareness temper their perceptions. Her presence inadvertently spurs growth in others, such as Mahiru Inami’s deepened understanding of Souta upon learning of his cross-dressing history—a testament to Kozue’s ripple effect on those around her.