Twenty-First Blood and Offense.
In a flashback to right after the events of the first three deaths at Sotoba, a woman named Motoko is shown to be overly protective of her children, going as far as to take them to school everyday. Eventually, as the mysterious deaths start piling up, Motoko's father-in-law dies. Her mother-in-law refuses to let Toshio perform an autopsy on the body, claiming that doctors care about the money more than their patients. Eventually Motoko's husband dies; then, her daughter falls ill. Slowly losing her sanity, Motoko carries her daughter over to the Ozaki clinic; however when she arrives, the clinic is closed (because Toshio is conducting experiments on his risen shiki wife.) She then rushes over to the Kanemasa clinic, which is also closed during the daytime. Motoko's mother-in-law shows up and scolds her for shaming herself in public, and states that her daughter is fine. However, her daughter dies, followed by her mother-in-law. Frightened, Motoko locks herself and her now-ill son in their home, where he dies in her arms and eventually rots. Kanami's mother returns as a shiki, obviously terrified by her new form; but Kanami looks after her, going as far as to feed her mother her own blood. Eventually, Toshio reveals the truth of the shiki to the villagers, who then launch an attack on them. Motoko seeks refuge at Kanami's where she discovers Kanami's risen mother, and tells the other villagers out of envy that her father-in-law took her entire family away, leaving her with nothing. Afterwards, the insane Motoko helps in the fight against the shiki. Eventually, Motoko takes a lighter and fuel up to Yamairi where she starts a fire, which quickly spreads and consumes her.