Tokyo: A magnitude 5.7 earthquake shook central Japan early on Sunday, shattering shop windows, sending people out of buildings and injuring at least 22, according to local media.
Japan's Meteorological Agency put the magnitude at 5.7, while the US Geological Survey recorded 5.5. Smaller aftershocks followed.
The shaking was felt across a wide area around Aichi Prefecture, including the city of Hamamatsu, the ancient capitals of Kyoto and Nara, and the nearby prefectures of Yamanashi, where Mount Fuji sits, and Gifu.
No tsunami warning was issued. The epicentre was deep enough that widespread structural damage was not immediately reported, according to preliminary information.
Disaster response teams have been put on standby and authorities are checking whether the injury count rises. Rail and flight services saw limited disruption, reports said.
Japan sits on one of the world's most seismically active belts, and tremors of this size are routine. Strict building codes and an early-warning system that pushes alerts to phones seconds before shaking arrives keep casualties low.
Officials urged residents to stay in safe locations and to expect further aftershocks through the morning. The Meteorological Agency said the shaking arrived before dawn and lighter tremors continued afterwards. Local authorities began inspecting buildings, and engineers are checking roads and bridges. Japan measures how hard the ground shakes on the shindo scale, which describes what people and structures feel rather than the energy released at the epicentre. Depth and distance from populated areas appear to have limited the damage. A nationwide early-warning system pushes alerts to phones seconds before the strongest shaking arrives.