Officials from Yamaguchi prefecture said the man was interviewed by police, but did not disclose any further information.
According to a report Japan's public broadcaster NHK, the man travelled from North Korea across the Sea of Japan by boat, saying "the man was drenched (in water) when police took him into custody".
The man, believed to be in his twenties, told police that he left Chongjin, the capital of North Korea's Hamgyong provice, on Friday night in a wooden boat, NHK reported.
He claimed to have jumped from the boat into the sea with a plastic container and drifted to Senzaki by Saturday morning.
The man said he was fleeing North Korea because he was being chased by police after he was caught watching South Korean videos, Japanese daily Asahi Shimbun reported.
The man was transferred to Omura Immigration Centre in Nagasaki on Sunday, where immigration officials will decide his future based on confirmation of his identity and claims of defection.
South Korea's Foreign Ministry told CNN it was "working to confirm the situation".
This website uses cookies.