Kanae Shinjō is a second-year student and a key member of the tennis club at Kameido High School, though her activities have very little to do with the sport itself. She serves as the club president, but this title is primarily a formality that underscores her role as the primary instigator of the group's chaotic and absurd adventures. Physically, she is a teenage girl with long pink hair, often styled with a side ponytail and a hair bobble, and green eyes. Her appearance is typically completed with a tennis uniform and sneakers, reflecting her nominal membership in the athletic club.

Kanae’s personality is the driving force behind the series' surreal humor. She is hyperactive, loud, and brash, possessing a seemingly limitless reservoir of energy that she channels into wildly eccentric and unpredictable behavior. Unlike her friends who have more defined gimmicks, such as being wealthy or acting as the voice of reason, Kanae is defined by pure, unbridled chaos. Her actions are not governed by logic or social norms, and she frequently breaks the laws of physics in casual and deadpan ways. For instance, she has been known to sleep while standing upright, submerge herself into solid ground as if it were water, or use a tennis racket strung with her grandmother's hair. Her mindset is impulsive and driven by whatever bizarre idea comes to mind, making her the catalyst for almost all of the club's nonsensical escapades, whether the goal is to visit a military base, aid an alien, or simply argue about trivial matters.

Her primary role in the story is to inject energy and absurdity into every situation, often to the bewilderment of those around her. She is the central engine of the group's comedy, with her manic ideas clashing against the contrasting personalities of her teammates. The core dynamic of her key relationships is built on this friction. She frequently unsettles Yuri Oshimoto, the club’s treasurer who acts as the reluctant straight woman and attempts to apply logic to Kanae’s insanity. She also interacts with Nasuno Takamiya, the wealthy and aloof member, and Marimo Bandō, the vice president whose calm or dim-witted demeanor can be easily swept up in Kanae’s wake. Beyond the immediate club, her life includes a diverse array of connections, such as her grandmother, a cousin named Mika-san who works at a kindergarten, and an acquaintance from the Yucatan Peninsula named Yucatan. These relationships often appear suddenly and contribute to the group's tangential adventures.

Kanae does not undergo significant character development in a traditional sense, as her role is to be a consistent, static source of disruption and comedy across the series' many short episodes and spin-offs. However, her actions reveal a notable ability for rapid-fire dialogue and comedic timing, allowing her to keep pace with the show's famously fast-paced dialogue. Her principal abilities are less about tennis skill and more about a surreal, reality-warping prowess. She can accomplish impossible physical feats, such as battling a tiger off-screen or splitting into two distinct entities, simply as a matter-of-course for her character. This defiance of physics and logic is her most defining trait, enabling her to propel the humor from one absurd moment to the next without any need for explanation or consequence.