The so-called Shimoda-Fuji in Shimoda City on the Izu Peninsula is a unique extinct volcano.

The inner part of a monogenetic volcano has a vertical passage of lava. In case of a young active volcano, lava periodically gushes out from its crater on top by way of a vertical passage.

But like a human, a volcano also becomes old. The sharp conical hill in the picture is an extinct volcano that used to be active a long time ago. The eruptions that once entirely covered this hill have been encroached and finally the giant rock made from cold lava in the vertical passage appears as a form of the sharp conical hill. Hence this hill, 190 meters high, is made up of just one huge rock that has originated from lava.