Ishinosuke Uwano is travelling back on a Ukraine passport

Ishinosuke Uwano was serving with the Japanese Imperial Army in Russia's Sakhalin Island when the war ended. He was last reported seen there in 1958.

The 83-year-old has now reappeared, in Ukraine, where he is married and has a family, Japanese officials say.

Mr Uwano is due to visit Japan for the first time in six decades on Wednesday.

He is expected to visit his surviving family members and friends in Iwate, 290 miles (467km) northeast of Tokyo, with his son before returning to Ukraine on 28 April, the AFP news agency reported.

The family's last reported sighting of him was on Sakhalin in 1958; after that they lost all contact with him.

In 2000, they recorded his disappearance under a Japanese law which says those soldiers who did not return after World War II can be registered as war dead.

His details were removed from the official family registry and, because of this, Mr Uwano must "return to Japan technically as a Ukrainian citizen with a Ukraine passport," a government official said.

The Japanese authorities are now restoring him to the family registry.

Strong interest

Mr Uwano's existence came to light last year after he asked friends in Ukraine to help him contact the Japanese government, which then sent officials to interview him in Kiev.

He was one of thousands of Japanese soldiers and civilians who were left stranded across the Pacific and in parts of China and Russia after the war ended.

Some were kept as prisoners and forced to work as slave labourers, others chose to remain of their own accord.

Why Mr Uwano remained in Russia, and how he ended up in Ukraine, has not been disclosed.

There is still much interest in Japan in the plight of former soldiers who never made it home, the BBC's Chris Hogg in Tokyo says.

Last year, Japanese officials returned empty-handed after going to a remote Philippine village to investigate reports that two former Imperial Army members were hiding there.