A second Maritime Self-Defense Force sailor suspected of wrongdoing was found hanged in the warehouse of the destroyer Asayuki at Sasebo base in Nagasaki Prefecture early Thursday morning, the Maritime Staff Office said.
Over the past several days, the 42-year-old sailor, a cook whose rank was given as petty officer first class, had been undergoing questioning by the MSDF's Sasebo district headquarters about unauthorized visits he made to China and South Korea, the office said.
He is believed to have committed suicide.
The sailor visited the two countries repeatedly between December 1999 and February this year, but did not have access to sensitive information, the office said.
"The dead officer was not in a position to handle classified information, and we believe there was no information leakage," the Maritime Staff Office said.
Another sailor, a 45-year-old petty officer first class, was suspended for 10 days in July for copying confidential internal data onto a CD-ROM and taking it outside the facility and for making repeat visits to China without permission.
That sailor was reportedly having an affair with a woman who worked at the same Shanghai karaoke bar linked to a honey trap espionage incident that led to a consular officer's 2004 suicide.
The headquarters is conducting an in-house investigation on whether other officials have been involved in data transfers or unauthorized visits overseas.