After Tokiko Kurosu returned home from school, she found her foster father's motionless body on the ground, likely from tripping and hitting a table corner. Despite the tragic scene, Tokiko seemed oddly unemotional.
The Kurosu family gathered at the hospital to grieve and were joined by police officers Koga and Yashiro to investigate. At first, the family was defensive, but as more deaths occurred - including another family member - suspicion began to fall on Tokiko. She had been present during numerous "accidents" before and after her adoption and her detached demeanor during them became increasingly concerning. Initially, Koga and Yashiro did not see a connection between the deaths, but as the body count rose, the remaining family members took matters into their own hands.
