Yui Yuigahama, a Class 2F student at Sōbu High School, radiates cheerful energy as the Service Club’s first client, joining to bake cookies for a crush before becoming its third member. Her light orange hair cascades into a loose side bun, complementing peach-red eyes and a relaxed uniform style—loose tie, absent blazer, knee-high socks—paired with a pale-pink festival yukata that underscores her playful charm. Beneath her sociable exterior lies a mediator adept at navigating social dynamics, her empathy earning her the metaphorical title of the group’s "glue," tied to her name’s kanji meaning "bind." Yet she grapples with self-doubt, concealing vulnerabilities behind a facade of kindness she once believed innate. Influenced by peers, she evolves toward self-awareness, confronting envy and reevaluating her perception of genuine compassion. Her arc centers on unrequited feelings for Hachiman Hikigaya, sparked when he rescues her dog, Sablé. She idolizes his selflessness but faces internal conflict as his rejection of superficiality challenges her "kind girl" persona. A pivotal three-way date forces her to reconcile her desires with her fear of losing friendships, culminating in a declined romantic proposal. Torn between selflessness and hidden selfishness, she supports Yukino Yukinoshita’s bond with Hachiman despite her own heartache, yet confesses her love while vowing to preserve her friendship with Yukino. This duality marks her growth in embracing both altruism and personal longing. Physically expressive, she comforts others through touch and exhibits comedic flair—donning a mistakenly gifted dog collar or panicking in haunted houses. Academically average, she shines in event coordination and karaoke, though her cooking lags. Her talkative mother mirrors her eccentricity, while trivia highlights her embarrassment over virginity and a skull-patterned phone symbolizing her role as the club’s inaugural client, layering her relatable adolescence with quiet complexity.