The volcano, about 200km (125 miles) west of Tokyo, erupted at about noon on Saturday, spewing ash and rocks.
Look for the effects on people and their responses to the eruption.
Search for bodies. On Sunday, the bodies of 31 hikers were found near the peak. More than 30 people are still missing.
Eruption Mount Ontake in Japan erupted on Saturday, sending a large plume of ash into the sky.