Nasuno Takamiya is a 16-year-old second-year student at Kameido High School and a member of the tennis club. Her extreme family wealth allows her to fund outlandish ideas for herself and others without hesitation, providing for extravagant or unusual requests easily.

She joined the tennis club after returning from Ngaoundéré, Cameroon, despite having no prior tennis experience. Within the club, she occasionally acts as the straight man when the most rational member, Yuri Oshimoto, is absent.

Her family owns a vacation cottage where she spends summers. During these times, she employs Yuri's younger brother and clubmate, Yota Oshimoto, as her butler. She assigns him meaningless tasks or chores governed by outrageous conditions and rules, often leaving Yota as the responsible counterbalance to Nasuno and her eccentric family.

Her mother, Ayano Takamiya, appears remarkably young and displays energetic, care-free behavior, sometimes joining Nasuno and Yota but leaving practical responsibilities to Yota. Her father, Alfred, resembles Colonel Sanders.

Nasuno exhibits capricious tendencies and generates peculiar ideas, like attempting to sunbathe in the rain using high-quality vegetable oil. She firmly believes money can resolve any situation, though a hidden stinginess occasionally surfaces beneath her lavish spending.