A housewife from Lower Sotoba who works in drive-in Chigusa. She's xenophobic to the point of unhinged mentality, and forbids her children to play near the motorway as she believes the outsiders will take them away. Her conditions visibly worsens after her father-in-law, Iwao, becomes a Shiki and kills her husband, daughter, mother-in-law and culminates in insanity when her son, the last member of the family, is also murdered.

Later, Motoko joins the Shiki extermination and betrays her friend Kanami's secret (that Kanami's mother Tae is now a Shiki and currently hiding in their house) to the villagers, leading to Tae's death and Kanami's abandonment of the village. She's obsessed with finding Iwao to avenge her children; her efforts are in vain as it's strongly implied that Iwao was already killed by Natsuno. At the end of the series, she becomes completely mad, and sets fire to the village and herself.