Ochō is a woman who appears in the Noppera-bō story segment of the anime Mononoke. She was born into the Umezawa family, and her father died when she was young. Her mother, who had married into the family, made it her life's purpose to restore the family's fortunes by raising Ochō to marry into a samurai household. From childhood, Ochō was subjected to strict training in various accomplishments, and her mother placed great expectations on her while rarely listening to her daughter's own feelings. Ochō genuinely loved her mother, and over time she learned to suppress her emotions and desires in order to become what was expected of her, gradually losing any outward expression.

She eventually married Sasaki Kazumasa, a retainer of the Hioki domain, after her mother pleaded for the match. The Sasaki family did not welcome her. Her husband regarded her as gloomy and treated her like a servant, and her mother-in-law looked down on her as well. Despite the harsh treatment, Ochō did not run away, because she could not bring herself to betray her mother's expectations. She endured her daily life quietly, finding small comfort only in looking at the sky through a narrow window. When her husband and his relatives were found dead, she was accused of murdering the entire family, sentenced to death, and thrown into prison.

In terms of personality, Ochō is calm, silent, and largely expressionless. Even with her execution approaching, she shows little emotion and does not try to defend herself or explain her actions. She avoids direct confrontation and keeps her inner world hidden from others. Her core motivation throughout the story is shaped by duty to her mother and the pressure to restore the family name, which leads her to endure suffering rather than resist it. At the same time, she is drawn to the prospect of escape from that suffering, which is why she responds to the masked man who appears in her prison cell.

Her role in the story is that of the accused criminal whose past conceals the nature of the mononoke. In prison she encounters the Medicine Seller, who is also being held there. He suspects that the massacre was not committed by human hands and questions whether she truly killed her family. Before he can learn the truth, a masked man claiming to be an ayakashi intervenes, drives him off, and takes Ochō away. The masked man professes his love for her and proposes marriage. Ochō accepts, and she feels genuine happiness during their wedding, which is presented as a series of staged visions. The Medicine Seller later returns and, in order to cut down the Noppera-bō, must relive Ochō's life and uncover the form, truth, and reason of the mononoke.

Her key relationships are central to the mystery. Her mother shaped her entire sense of duty and expectation, while her husband and mother-in-law represent the cruelty she was forced to accept without complaint. The masked man is a being born from her own heart who was manipulated through a fox mask by the Noppera-bō, and the Medicine Seller speculates that the Noppera-bō itself harbored a small affection for Ochō. The Noppera-bō attached itself to her weakened heart and repeatedly showed her visions of the Sasaki family's destruction, offering her temporary comfort while also binding her to the very situation she wished to escape.

Ochō's development comes through these staged illusions and the Medicine Seller's investigation. As he walks through the events of her life and forces her suppressed wishes to the surface, she is confronted with the truth behind the massacre and the reason the Noppera-bō was able to take hold of her. Once the truth and reason are revealed, the mononoke is cut and she is released from its influence. She does not possess supernatural abilities; her defining traits are emotional concealment, endurance, and a carefully maintained calm that allows her to survive hostile surroundings until the hidden feelings behind that calm are finally brought into the open.