Sanae Ōmura is Takeshi Ōmura's aunt and Motoko Eguchi's mother. After the destruction of Takeshi's home, she takes guardianship over him. When Elle Ōmura arrives and joins the family as Takeshi's stepsister, Sanae extends her guardianship to include Elle.

Sanae possesses a reserved personality and feels self-conscious about her age. She favors wearing white clothing. She works professionally at an antique shop. Despite her typically shy nature, she exhibits impressive physical strength and demonstrates combat proficiency.

Sanae holds a personal interest in clothing design and construction. She actively creates garments and frequently attempts to persuade Takeshi to wear dresses she has made, stemming from her lack of understanding regarding his discomfort with such attire.