A strong earthquake with a preliminary magnitude of 5.5 has jolted the Ibaragi Prefecture near Tokyo.
Japanese public broadcaster NHK said there were no immediate reports of damage or injury.
The earthquake also had no impact on the tsunami-crippled Fukushima nuclear power plant.
No tsunami warning was issued.
The U.S. Geological Survey measured the quake with an initial magnitude of 5.2.
On March 11, Japan's northeast coast was struck by the strongest quake on record in Japan, and a massive tsunami, which triggered the world's worst nuclear crisis since Chornobyl 25 years ago.
The disaster left some 23,000 dead or missing.
compiled from agency reports