Yuika Serizawa shares a childhood friendship with Akihito and Umi Hayasaka, having attended the same junior high and high school. Her happy-go-lucky and cheerful nature sustains a year-round positive demeanor, making her popular among peers. Academically gifted, she excels in studies but struggles with sports. Despite a wealthy family background, she actively experiments with new cooking techniques as a dedicated member of her school's cooking club.

Physically, she stands 158 cm tall with a slim build weighing 47 kg and measurements of 84-58-83 cm (C-cup bust). She possesses violet eyes and straight, shoulder-length brown hair styled with spiky bangs parted to the side. Her typical attire is her school uniform, consisting of a capelet, ribbon tie, pleated skirt, knee-high socks, loafers, and a ribbon hair accessory.

Her history includes being Akihito's first love during junior high. His confession to her ended unsuccessfully, reverting their relationship to a platonic friendship. Upon reuniting in high school, she behaves unchanged, leaving Akihito uncertain if she ever truly understood his past romantic feelings.

In their high school class, she is Akihito's classmate seated directly behind him. Her friendly, approachable nature underpins her popularity. She maintains an optimistic and kind personality, though occasionally displaying airheaded tendencies. Her commitment to cooking reflects a willingness to challenge herself despite her affluent upbringing.

Across official media adaptations, her background story shows no significant development or changes. Her role consistently emphasizes her status as a supportive childhood friend and classmate within the school environment.