The Skull Starts Moving in the Dark Night: Fourth Season

Mr. and Mrs. Onishi lost their only son, Shota, to suicide due to bullying. The school denies the fact of bullying, and his wife Yoshie continues to pursue the facts, but he feels regretful. And 30 years later ... The couple has been living quietly, but Yoshie suffers from dementia and gets into a car accident. Satoru, a husband who went to get a change of clothes for his hospitalized wife, discovers a record of his wife's terrible revenge ...!