The Japan Coast Guard said Wednesday that it had received an emergency call saying an Osprey tilt-rotor plane had crashed off the coast of Yakushima island in Kagoshima Prefecture.
According to the 10th Regional Coast Guard Headquarters, the call came around 2:45 p.m. and eight people were said to be on board the plane, which belongs to the U.S. military. The coast guard later revised the number of people to six.
The regional headquarters dispatched a patrol boat and aircraft to investigate the details.
A coast guard source said that the incident was reported by the crew of a fishing boat near the site. The apparent Osprey aircraft is believed to have been trying to land at an airport in Yakushima.
The Yakushima airport office in Kagoshima Prefecture said the Osprey may have crashed in an area about 2 to 4 kilometers away from the airport.
According to the coast guard, a man was found unconscious near the suspected crash site along with what appears to be debris from an aircraft. The man was later confirmed dead, it said.
Prime Minister Fumio Kishida said the U.S. would be asked to confirm the details of the incident.
Okinawa Gov. Denny Tamaki told reporters that he intends to ask the U.S. military to suspend all Osprey flights in Japan until it finds out what caused the crash.
Ospreys, capable of taking off and landing like a helicopter as well as cruising like a plane, have a track record of accidents and mishaps both in Japan and abroad.
In 2016, an MV-22, the variant used by the U.S. Marine Corps, crash-landed off Okinawa. Crashes also occurred in Australia in 2017 and August this year, each time leaving three crew members dead.