Six people were found dead on Monday at a home in Takachiho Town in Miyazaki Prefecture, southwestern Japan.
Police suspect murder as wounds were visible on some of the bodies. Most of the victims are believed to be family members. One was a small girl.
Police are looking for the missing son of the family head.
Sources close to the investigation said a car believed to be the son's was found at a parking lot in town. A man's body was found under a bridge nearby.
The identity of the body is being confirmed, and investigators are looking into whether the 2 incidents are connected.
Police received a call earlier Monday from a family member living outside the town who said no one was answering calls to the home in town.
A police officer went to the home and found a woman's body outside. Three male and 2 female bodies were found inside.