|Relatives, etc.||Kazuyuki Izumi (Husband)|
Shinichi Izumi (Son)
|Anime debut||Episode 1|
|Manga debut||Chapter 1|
|English Voice||Allison Sumrall|
|Live Action||Kimiko Yo|
Nobuko Izumi (泉 信子 Izumi Nobuko) is the wife of Kazuyuki Izumi and the mother of Shinichi Izumi, who was killed and decapitated that her headless corpse was taken over by a parasite that needed a female body to transfer to.
Nobuko is a fair-skinned woman with short brown hair and brown eyes. She usually wears a white shirt with a pink coat and slippers. She has a burn mark on her right hand and wrist and had sustained this injury when she saved her son, Shinichi, from getting doused with boiling hot oil in the past. When she was younger, she is shown to have longer hair.
Nobuko is a kind and attentive woman who gets emotional easily. As Shinichi's mother, she helped him many times and listens to him and Kazuyuki, her husband. She showed a lot of concern when Shinichi began to change from his experiences, eventually feeling as if he had become unrecognizable as her son. However, while Shinichi felt guilt over her scar, she didn't think it was something to fuss about.
During day-to-day life, she was slightly disgusted by her husband reading gory news about the Mincemeat Murders aloud, and startled when he commented that Shinichi probably wanted privacy to "jack off".
In the past, Nobuko saved a young Shinichi from getting burned by catching a pot of boiling hot oil as it was falling off the stove and gaining a large scarring burn on her hand and wrist in the process. Kazuyuki Izumi came immediately to see what had happened and takes notice of her injury. Upon realizing that she had burned her right hand, she screams and turns to the kitchen's wash basin to run water over it.
This scar serves as a reminder to Shinichi of his mother's sacrifice for him, and later causes him to hesitate in the process of killing the parasite who had taken over Nobuko's body.
After Shinichi's hand is infected with a parasite, Nobuko notices some differences in her son's behavior and personality. Although she doesn't express much worry at first, when she mentioned that her and Kazuyuki wanted a vacation, Shinichi was vehemently against it at first and then at the end of the day he says that he's fine with them going on the trip, which causes her to cry. She tells him that his personality changed and that he didn't seem to be her son anymore. Shinichi lies to her, saying that was afraid of being alone, but then decided he could invite some friends over so it would be fine. The next day they leave the house to Shinichi and go on their vacation.
Near where they are staying, there is a car crash involving a man and a parasitized woman. The parasite's host is fatally damaged, and she decapitates the man to take over his mostly-uninjured body. Meanwhile, Nobuko calls home, asking Shinichi if he's doing alright. Half-asleep, Shinichi tells her that he's fine. The parasite stumbles down the side of the road as the man's body begins to reject it, and it decides it needs a woman's body to function.
As Shinichi's parents leave the small hotel they were staying at to go for a walk, they stop at a cliff by the sea to take in the beautiful view. Nobuko remarks that she would like to bring Shinichi there someday. A few moments later, her husband watches in horror as the parasite appears behind Nobuko and decapitates her. He manages to escape and later phones home from a payphone to tell Shinichi what happened to his mother, then collapses. He is later brought to Sakurazaki Hospital.
The parasite soon makes its way to the Izumi household. Unable to believe she is dead, Shinichi attempts to apologize for the scar on his mother's hand and refuses to allow Migi to defend him from the parasite impersonating her. He is then fatally injured, only surviving due to Migi's efforts to rebuild his heart. After he awakens, he heads to Sakurazaki Hospital to protect his father. Shinichi eventually avenges his mother by killing the parasite who killed her with assistance from Mamoru Uda and Jaw (then named Parasite), but remains unable to grieve for her.
- The name Nobuko means "trust, believe" (信) (nobu) and "child" (子) (ko).
- Nobuko's surname Izumi means "spring, fountain" (泉).