Enjoy spectacular scenery from the observation deck on the peak of Mount Kasayama, evidence of 100 million years of geological history in the Hagi area. The flat islands which can be seen in the Sea of Japan constitute a volcano which erupted between 60,000 and 210,000 years ago. These islands belong to the same “Abu Volcano Group” as Mount Kasayama, which includes nearly fifty small volcanoes, with the epicenter to the north east of Hagi City.