Pipimi is a 14-year-old girl distinguished by her tall stature, long blue hair, light blue eyes, and a constant prominent red bow. She consistently wears a sailor uniform, white socks, and brown shoes. Her physical design enables adaptability across art styles while preserving recognizable elements like her height relative to Popuko and a blue-and-purple color scheme.

Characterized by stoicism and an even temper, she rarely displays anger, contrasting with Popuko's volatility and positioning Pipimi as the calmer, more strategic partner. She frequently restrains Popuko's impulses yet simultaneously enables or participates in violent acts. Pipimi exhibits understated menace, casually discussing or executing extreme violence—assassination or vehicular homicide—with detached calmness. She demonstrates occasional distractibility, zoning out during conversations to contemplate her idol, Hellshake Yano. Despite her violence, she shows deep loyalty and protectiveness toward Popuko, reacting harshly to those who mock or threaten her. This bond occasionally implies romantic feelings through affectionate gestures like heartfelt compliments or shared idealistic scenarios.

Pipimi possesses extensive supernatural and combat capabilities. Her powers include superhuman physical attributes, mastery of weapons accessed via dimensional storage, flight, duplication, invisibility, tornado creation, reality warping, spatial manipulation, transformation, and planetary-scale self-destruction. Additional abilities encompass fourth-wall awareness, plot manipulation, immortality, regeneration, and resistance to heat, age manipulation, and mental interference. She employs these powers erratically, often for comedic or chaotic effect rather than consistent heroic or villainous purposes.

Her narratives lack linear development but feature recurring themes of chaos and absurdity. She has ruled a post-apocalyptic world using an army of Popuko clones, hired Popuko for assassination missions, participated in global destruction events like splitting Earth, and engaged in kidnapping, torture, and decapitation, often for trivial reasons. Despite this, she intermittently performs heroic acts like sealing demonic entities or aiding multiverse preservation. Her actions remain tonally inconsistent, blending extreme violence with parody and surreal humor without narrative consequences or character evolution.

Her relationship with Popuko is the core of her character, defined by codependence and shared chaotic agency. They function as a unit across disparate scenarios, with Pipimi alternating between acting as Popuko's restraint and her accomplice. This dynamic reinforces their roles as agents of unstructured absurdity, resisting fixed moral alignment or narrative progression.

No concrete background story or character development occurs across official media. Her origins, chronological age, and history remain undefined or contradictory, such as fossil records suggesting 102.5 million years of existence. Her traits and capabilities remain static, serving as vehicles for episodic humor rather than structured growth.