A Japanese tourist crossing South Australia's Nullarbor Plain by bike took his own life, a coroner has ruled.
The body of Katsushi Ohata has never been found after a collection of his personal property was recovered in March 2015 near the Southern Ocean, about 50 kilometres west of Nullarbor.
He had last been seen about 10 days earlier in Ceduna where he bought a bike while spending several nights in a cabin at a caravan park.
Deputy State Coroner Anthony Schapel said the evidence presented to his inquiry supported a conclusion that the 51-year-old had taken his own life.
Items at the scene included $4420 in cash along with credit cards in Mr Ohata's name, which had been cut up, and other personal possessions.
Mr Schapel said it was "fanciful" to suggest that someone else may have been involved or that Mr Ohata had faked his own death.
He found "on the balance of probabilities" killed himself.
"I do not know what motivated him to do so."
Mr Schapel said very little was known about Mr Ohata including his physical and mental health history.
He said the man's family in Japan declined to participate in the investigation despite the efforts of various Australian authorities and agencies.
"What little successful communication there was with Mr Ohata's family did not give rise to any indication that he had returned to Japan," the coroner said.
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