Volcanic earthquakes have continued at Mount Hakone, located in a hot spring resort town outside Tokyo.
Japan's Meteorological Agency warns of a possible eruption, and large volcanic rocks falling around the crater in the Owakudani valley.
The agency raised the volcanic alert level to two on a scale of five on Sunday.
Officials say volcanic earthquakes have continued since Saturday, mainly west of Lake Ashinoko. The area is considered to be the epicenter of the recent activity.
The agency observed 74 volcanic earthquakes on Sunday, and four on Monday by 3 p.m..
The town of Hakone has restricted traffic from going near the crater since early Sunday, affecting businesses.
On Monday, town officials let vendors into the area for two hours to pick up goods.
A wholesaler of dairy products said he came to pick up materials for ice cream, and that he hopes the situation returns to normal soon.
Services of the Hakone Ropeway have been halted. A tourist from Belgium said he is disappointed because he was looking forward to experiencing the view. He said he will take a boat trip instead.