Yui Yagi exhibits exceptional intellectual capabilities with an IQ of 180, excelling in analytical thinking and problem-solving. This cognitive strength contrasts with significant interpersonal difficulties, as she struggles to interpret and respond to others' emotions, fueling an underlying desire for social connection and acceptance. Her behavioral traits include a limited and unconventional sense of taste, leading her to consume primarily coffee and snacks. Physically, she features a recurring butterfly motif and mahjong-themed accessories like a hair clip. Her attire typically combines a knit sweater, a jacket with detailed cuffs and pockets, and tights of varied sheerness. Narratively, she appears in mahjong matches and shrine-related activities alongside other characters. Her role expanded in the sequel series to include diverse scenarios such as live streaming endeavors. A licensed figure depicts her in the "Full Bond" in-game outfit, seated on a tree swing with a paved road base and floral arrangements. This portrayal emphasizes a juxtaposition of outward composure and subtle vulnerability through her posture—one leg extended outward and the other drawn closer to her body. The figure’s specifications list her height as 1.75 meters at full scale, reduced to 250 millimeters in 1/7 scale replicas.