Ageha is a young female shinigami who comes from a wealthy and elite family known for their success in taking down damashigami, a type of evil spirit that lures humans to the afterlife for profit. She possesses a confident and assertive demeanor, but her most defining traits are her air-headedness and impulsive nature. Ageha frequently acts before she thinks, which often leads her into various forms of trouble. This lack of foresight is compounded by her tendency to throw her considerable wealth around without a second thought, making her an easy target for scam artists and the fake products sold by damashigami.

Her primary motivation is a deeply personal one. She is driven by the shame and anger she feels toward her older sister, who abandoned their family's proud legacy to join the very damashigami company they swore to destroy and became the secretary and girlfriend of the company's president, Sabato Rokudo. In the wake of this betrayal, Ageha has taken it upon herself to hunt damashigami while searching for her missing sister. Her mission is to find her sibling and exact revenge on anyone associated with the damashigami company. This mission becomes complicated when she meets Rinne Rokudo, a fellow shinigami and high school student. Initially, she looks down on him for his poverty, but after learning he is not like his father, Sabato, she develops strong romantic feelings for him. Her role in the story is therefore twofold: a determined damashigami hunter and a comedic, lovesick rival to Sakura Mamiya, whom Ageha views as her primary competition for Rinne's affection.

Key relationships define much of her character arc. Her unrequited love for Rinne is a central focus, leading her to concoct various schemes to win him over, often with disastrous and humorous results. She considers Sakura a rival in love, though Sakura makes attempts to be friendly with her. Ageha has a contentious history with the black cat Oboro, who is her contracted partner; she fought with him as a child and even buried him under rubble during one of their early missions. She also holds a deep hatred for the shinigami Kain, both for insulting her and for his actions against Rinne. Her relationship with her own black cat, Oboro, is built on a shaky foundation of bickering and a contract she holds over him, though Rinne once reminded them their partnership requires trust.

Throughout the series, Ageha shows little to no development in her professional abilities or her impulsive personality, often leaving her shinigami duties and her room in a state of disarray. However, her personal journey sees her shifting her primary focus from simply hunting damashigami to aggressively pursuing a relationship with Rinne, becoming more preoccupied with romance than her family's mission. Her notable abilities as a shinigami include the use of coins as weapons, which she throws at her targets. She also possesses standard shinigami tools and techniques, such as a special bow that allows her to become visible to humans, though her sloppiness often leads to her misplacing important items like her shinigami license.