A Japanese man in his 50s has been detained in the Chinese province of Hunan since July, possibly for alleged spying, a Japanese government source said Wednesday.
In September, a Japanese professor from Hokkaido University in Sapporo was held in China on suspicion of espionage, but he was freed earlier this month.
The Japanese national detained in Hunan is being held in Changsha, and has had access to consular services, the source said, adding that he is in good health.
It is unclear why he has been held by Chinese authorities.
Since 2015, more than 10 Japanese citizens have been detained in China on various charges, including espionage.
China has been stepping up its scrutiny of foreign organizations and individuals in the name of protecting national security since President Xi Jinping came to power in 2012.
Not only Japanese, but a number of other foreign nationals have also been held in China, particularly after a counterespionage law took effect in 2014 and a national security law in 2015.
The latest incident came amid a recent thaw in Sino-Japanese relations long frayed over wartime history and territorial issues.
China and Japan have promoted reciprocal visits by their leaders. Prime Minister Shinzo Abe traveled to Beijing in October last year, while Xi paid a visit to Osaka in June to attend the Group of 20 summit.
The two neighbors have also agreed on a visit by Xi to Japan next spring as a state guest, with Abe inviting the Chinese president to come "when the cherry blossoms bloom."