China on Saturday released the last of four Japanese citizens detained on suspicion of illegal filming inside a military zone in the northern province of Hebei, DPA reported.
Sada Takahashi was released on bail by state security police in the provincial capital, Shijiazhuang, the official Xinhua news agency reported.
It quoted police as saying Takahashi had been "instructed to write a statement of repentance" and was no longer under "residential surveillance."
Takahashi had "left the place where he was residing under surveillance after going through legal procedures," it said.
The report did not say if Takahasi would be allowed to leave China or if he still faced charges.
Three other Japanese men were released on September 30 after "admitting to having violated Chinese law" by "intruding in a Chinese military zone without authorization."
Takahashi, 57, was reportedly investigated for "illegally videotaping military targets."
Japanese media said the four men detained in China were employees of construction firm Fujita Corp and a local subsidiary.
They were reportedly working on a government-backed project to clear remnants of chemical weapons abandoned by Japanese troops during World War II.
Chinese officials and state media did not report why the four men were in China.