Police in Japan have found the bodies of nine people in what they suspect were two group suicides.
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.
Police were reportedly alerted to the Chichibu incident by a passer-by on Friday.
When they got the forested site, they found the bodies of six people - reported to be in their 20s - inside a people carrier vehicle.
Chichubu police spokesman Ichiro Fukumoto told the AP news agency that at least three charcoal stoves were found in the car, and the windows were sealed with tape.
Suicide pact deaths have shocked Japan
The stoves - which generate the poisonous gas carbon monoxide - were reportedly still smoking when the bodies were found.
Police are still investigating how the six met, but their apparent method of suicide appeared to be very similar to several other group suicides which were arranged over the internet.
A separate group of bodies - those of a young man and two women - were found earlier this week near Hirosaki, in Aomori prefecture.
The bodies were discovered on Wednesday, in a sealed car in the foothills of a mountain, though the deaths were only reported on Friday.
In this case, the three people had first met at a hospital, and had recently been telling people that they wanted to die, police told Kyodo news agency.
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.
The number of people killing themselves in suicide pacts made over the internet - while still small - has been rising sharply.
Police said last month that 91 people had died in the pacts in 2005, compared with 55 in 2004 and 34 in 2003, when the records started.
Alarm at the rise has led to increased vigilance by internet service providers, who now report suspected suicide pacts to the authorities.