Four people have been found dead in central Japan in the third suspected group suicide in less than a week.
The bodies of the three men and a woman were found in a parked car in Shizuoka prefecture, 150km (93 miles) west of Tokyo, a police spokesman said.
The windows of the car had been sealed with tape, and there were several charcoal burners inside.
The bodies of nine people were discovered last week in two separate cases of suspected group suicide.
The four people involved in the latest incident were all believed to be in their 30s. The car in which they were found was parked on a lonely mountain road.
Last Friday, the asphyxiated bodies of five men and a woman were found in a car at Chichibu, near Tokyo, while three more bodies were found near Hirosaki.
Police are investigating whether the Chichibu six met via the internet.
Japan has one of the highest suicide rates in the world, and internet pacts are thought to appeal to those who are scared to die alone.
The number of Japanese committing suicide has been rising steadily in recent years - more than 34,000 Japanese took their own lives in 2003, according to the National Police Agency.