Fujino Ninno is an adult woman characterized by purple eyes and chest-length brown hair. She serves as Takeshi Ninno's stepmother within their non-biological family unit, acting as a central figure in the household's hidden tensions.

She enforces a coercive sexual relationship upon Takeshi, compelling his participation through the threat of revealing their encounters to her daughter, Shinobu Ninno. This leverage exploits familial bonds to ensure Takeshi's compliance, driven by his desire to preserve Shinobu's perception of him.

Her relationship with Shinobu is marked by profound distance and neglect, attributed to undisclosed "ominous reasons" that fuel Shinobu's refusal to interact with her. This strained maternal connection coexists with the concealed activities involving Takeshi, creating a complex duality of domestic conflict.