Kyoka serves as the guardian and aunt to the protagonist, Moena. She is the owner of a maid cafe located on a college campus, where Moena works as a waitress. Having taken in her niece after Moena’s mother passed away when Moena was an infant and her father disappeared, Kyoka has been a stabilizing presence in the young girl’s life. She is depicted as a notably buxom woman, a physical trait that is often remarked upon by other characters.

In terms of personality, Kyoka is caring and maternal, particularly in her concern for Moena’s well-being and social development. She expresses gratitude to Moena’s friend Hasumi for helping bring Moena out of her shell, as she had worried that Moena was becoming a wallflower who never left the campus. Kyoka is shown to desire a normal, happy life for her niece, once devising a plan for Moena to meet boys.

Kyoka’s role in the story extends beyond that of a simple cafe owner. She is deeply connected to the central conflict involving the Angel System. She is aware of the Geobloods, the antagonistic force of the series, and is concerned about the strain placed on Moena’s body as the primary Angel unit. Furthermore, Kyoka herself becomes a key figure in the project. She is associated with a scientist named Isato and is subjected to experiments to help complete the second system of the Angel project, enduring intense pain for this purpose. This involvement leads to her being kidnapped by the villain Karin, who is revealed to be Kyoka’s wife.

Key relationships define her character arc. Her marriage to Karin is complex and adversarial, as Karin kidnaps and holds her captive at Dark Mother’s Castle to use her as leverage or for further experimentation. While captive, she is subjected to scans and procedures, including the implantation of a tracking device. Her relationship with Moena remains central, as her capture becomes a primary motivation for the angels to act, and she is eventually found and rescued.

Kyoka does not possess superhuman combat abilities like the series' angels. Her primary function within the narrative is that of a test subject and a damsel in distress. Her notable characteristics are her physical endurance and her willingness to sacrifice her own comfort and safety for the sake of the Angel System’s development, as she insists on continuing painful experiments to help finish unit two. Her development sees her transition from a nurturing guardian to a captive whose body is used as a vessel for the antagonists’ schemes, yet she remains a figure for whom the heroes fight to protect.