A Japanese man, who had been sentenced to prison in China in 2018 on spying and other charges, was released and arrived in Japan on Thursday, the government said.
Among Japanese citizens detained in China on espionage and other similar charges since 2015, the 59-year-old has become the first to return to his home nation after completing a full sentence.
The Japanese government has denied he engaged in spying. Details of the alleged espionage have not been disclosed.
According to a Japanese government source, the man was released from prison in Dalian, Liaoning Province, on Wednesday. He left Dalian for Narita, east of Tokyo, by air on Thursday afternoon. He is believed to have tested negative for the novel coronavirus.
The man from Kanagawa Prefecture was detained by Chinese authorities in May 2015 when he visited Dandong in Liaoning Province, close to the border with North Korea.
In September that year, the Chinese Foreign Ministry acknowledged that the country had arrested the former defector from North Korea on suspicion of espionage and that it had notified the Japanese side of his detention.
The People's Intermediate Court in Dandong eventually sentenced the man to five years in prison on spying and other charges in July 2018, while ordering him to leave China after serving his time.
Sources close to him said the man moved with his family to North Korea from Japan in the 1960s under 1959-1984 repatriation programs. Later, he defected from North Korea with some of his family members.
He returned to Japan in 2001 after going through China, Southeast Asia and South Korea, the sources added.
Since a counterespionage law and a new national security law came into force in 2014, the Chinese leadership under President Xi Jinping has been intensifying its watch over foreigners.
So far, at least nine Japanese have been indicted for alleged involvement in spying. Seven have faced prison sentences, with two appealing to a superior court. Meanwhile, five people have returned to Japan without being tried.