Absolute Anime

Satoko is Rika's best friend. Since both of their sets of parents are dead, they live together. Depending on which chapter you watch, Satoko's parents either died by accidentally falling off of a cliff while on vacation or Satoko pushed them. Satoko also has an older brother, Satoshi, who she says left town. However, he is just receiving treatment for Hinamizawa Syndrome. She calls him "Nii-Nii," after the Japanese word for big brother, "O-niisan." Like her brother, she also has Hinamizawa Syndrome, but she takes shots for it. However, she does not know this; she thinks the shots are some form of supplement. When her abusive uncle comes into town and she is forced to stay with him, she stops taking the shots and has a panic attack.

She loves to set traps and pranks, which come in handy later in the series when the club members are picking off Takano's henchmen.

Satoko blames Satoshi's absence on the fact that she clung to him too much after their parents died. She firmly believes that he will come back once she becomes stronger and less whiny. She takes this so far that she puts up with weeks of physical and emotional abuse from their uncle in one chapter and being stabbed to death. Ironically, she was being stabbed by Shion for "making Satoshi go away." During that, she adamantly refused to cry out in pain and made comments like "Nii-Nii, can you see how strong I am?"