Ayano Katase is a female doctor working at a hospital run by her parents. She is depicted as a professional woman with a clear and urgent personal goal: to have a child. This desire is not merely a personal wish but a condition she must fulfill to inherit her family's hospital, making the need for a child a pragmatic requirement for her career and future.

Ayano is introduced as an eager and determined individual who takes an active role in pursuing her objectives. Her path crosses with the male protagonist, Taika Inaba, at a speed-dating event where the two hit it off. However, Taika abruptly flees due to his own anxieties, creating an initial complication. In a twist of fate, Ayano is later revealed to be the doctor Taika consults for his medical condition, re-establishing their connection in a professional setting. This discovery leads to an unusual arrangement, as the pair decide to enter into a secret, contractual marriage with the singular goal of conceiving a child within a year.

Ayano's primary role in the story is as the female lead and the catalyst for the central premise. Her professional position as a doctor is integral to the plot, as it brings her back into Taika's life after their initial encounter. Her determination to start a family drives the narrative forward, forming the basis of the protagonists' agreement. Key relationships for Ayano are centered on Taika Inaba, her contractual partner and patient, whose personal struggles become intertwined with her own mission. Her family background, specifically her parents who run the hospital, provides the underlying motivation for her quest to have a child. While Ayano is portrayed as a focused and driven professional, details regarding her personal development over the course of the series or any notable abilities outside of her medical expertise are not detailed in the source material.