Nagafuji Taeko attends high school as a classmate of Hougetsu Shimamura, introduced during their first year. She maintains a friendship with Shimamura while sharing a deeper, longstanding bond with Hino Akira that originated in kindergarten. Throughout their education, Nagafuji and Hino remain in the same class. Her family owns a butcher shop where she occasionally assists, though she feels ineffective in this role.

Physically distinctive, Nagafuji matches Shimamura in height and sports wavy purple shoulder-length hair, dark blue eyes, and red glasses. Her fuller physique attracts attention, especially from boys, fueling recurring self-consciousness about her breast size.

Nagafuji displays a consistently absent-minded and laid-back demeanor, often seeming detached or forgetful. Her careless habits invite frequent teasing from Hino, yet she remains cheerfully unaffected. Despite her ditzy nature, she earns decent grades—a contrast highlighted by an elementary school report noting she "only looks responsible."

Her interests include a peculiar fixation on boomerangs. This hobby becomes relevant when she suggests a boomerang as a Christmas gift for Shimamura to give Adachi. Later, she helps Adachi master its use, possibly recognizing it as her recommended item without probing further.

Nagafuji shares intense physical affection with Hino, frequently kissing her forehead and sparking embarrassment. They often stay at each other’s homes, sharing baths where Nagafuji comforts Hino during emotional talks and permits intimate gestures like breast-touching. Their dynamic includes mutual jokes about Nagafuji’s forgetfulness, which she takes in stride.

Daily limitations, such as poor bicycle skills, force her to depend on Hino for transportation. Nagafuji’s role remains consistent—supportive friend, wrestling with insecurities and hobbies—without radical development.