Hisae is the wife of Heizou Hasegawa, the chief of the special police force known as the Hitsuke Tozoku Aratamegata, in the anime Onihei. She is an adult woman with brown eyes and black hair that is typically worn up. As a character who appears in most episodes, she primarily serves as a supporting figure in her husband's life, representing the domestic and emotional anchor at the Hasegawa residence.

Hisae is characterized as a good-willed and attentive woman, demonstrated through her constant care for her family, particularly her mischievous adoptive daughter, Ojun. She often engages in conversations with Heizou about matters that weigh on him, always responding with empathy and genuine concern. Rather than being merely passive, she shows a willingness to confront difficult truths when necessary, as seen when she agrees to reveal a secret from her past to protect her child. There is also a subtle tension in her relationship with Ojun that stems from the circumstances of the girl's adoption, but she ultimately comes to a deeper understanding of why Heizou chose to raise the child, showing her capacity for emotional growth and acceptance.

The story provides a significant look into Hisae's background, revealing that she was not always the reserved and respectable wife she became. As a young girl, she was neighbors with both her future husband Heizou and a young man named Kondo Kanshiro. She fell in love with Kondo, who came from a respected samurai family, but he later betrayed her through a series of vices including drinking, robbery, and murder. This relationship left her honor compromised and her future uncertain. It was Heizou who, despite knowing the truth, volunteered to marry her, thereby saving her from social ruin. This act of kindness from a man who had himself been a wild youth deeply shaped her life and her loyalty to him.

Her primary role in the narrative is as Heizou's wife, and she appears most often within the walls of their home. While she is not a frontline participant in the police work, her presence is crucial for understanding Heizou's character, as she is one of the few people who sees his mild and compassionate side. Her most notable moment in the story comes when a figure from her past, Kondo, kidnaps her daughter, forcing her to confront the history she thought she had left behind. This event reveals her strength and her willingness to sacrifice her own reputation to save her child. Her own past as a "bad girl" creates a parallel with Heizou, whose youth was also marked by wild behavior, and her marriage to him saved her from a terrible future. This shared history reinforces their bond and explains the non-judgmental understanding between them.

The character shows development primarily in her evolving relationship with her adoptive daughter, Ojun. Initially, there is a palpable distance between them, but as she listens to Heizou recount his own troubled childhood, she gains insight into his motivations for adopting Ojun. At the end of this story, she looks at the sleeping girl with a newfound sense of acceptance and understanding, signifying a key moment of emotional growth in her role as a mother. Her abilities are not those of a warrior or investigator; instead, she excels in the domestic sphere, managing the household, raising children, and providing a stable and empathetic presence that supports her husband in his demanding and often violent line of work.