Nasuno Takamiya is a 16-year-old female second-year high school student from an extremely wealthy family. She routinely deploys her vast wealth to enable outlandish ideas and solve problems. After returning from a trip to Ngaoundéré, Cameroon, she joined the school tennis club despite possessing no tennis knowledge.

Within the main series, she interacts with other tennis club members, occasionally serving as the straight man when Yuri Oshimoto is absent. Her personality blends a parsimonious, deadpan demeanor with a tendency to instigate or amplify absurd situations, often accompanied by a through-ted grin. Physically, she has brown hair, aubergine-colored eyes, stands 153 cm tall, and weighs 55 kg. She is noted as the curviest and most buxom among the main characters, which occasionally contributes to fanservice moments.

Her spinoff series, *Takamiya Nasuno Desu!*, focuses on her daily life outside the tennis club. During summer break, she stays at her family's vacation cottage, employing Yuri's younger brother, Yota Oshimoto, as her butler. She frequently orders him to perform meaningless or outrageous tasks, with Yota acting as the primary straight man to her antics. Her family includes her mother, Ayano Takamiya, who appears extremely young and energetic, and her father, Alfred, who resembles Colonel Sanders. These interactions highlight her privileged upbringing and eccentric environment.

Across all media, Nasuno consistently leverages her wealth for convenience or amusement. She exhibits mild disdain for certain club members like Marimo Bando yet participates in group activities. Her core traits of wealth-driven solutions and comical seriousness remain consistent, showing no significant development. Spinoff interactions reveal occasional moments where she drops her reserved act, engaging in whimsical behavior with family or visiting tennis club members.