A 5.5-magnitude earthquake hit near Japan's east coast on Saturday, the US Geological Survey said.
The moderate quake hit at a shallow depth of 11 kilometers (6.8 miles), 244 kilometres northeast of Tokyo, just after 5:00 am (2000 GMT).
Japan sits at the junction of four tectonic plates and experiences a number of relatively violent quakes every year. But rigid building codes and strict enforcement mean even strong tremors often do little damage.
On Wednesday, a 6.3-magnitude quake hit 18 kilometres north-northeast of the town of Daigo, but there were no reports of injuries or damage.