5700 years ago, after a tremendous naturally occurring explosion, the leftover crater filled with water and became a lake.

Facing Lake Unagi is a town that has barely changed for many years.

Surpisingly, steam at very high temperature rises from the ground there. This is proof that Lake Unagi is still an active volcano.

Famous for its onsens, the area of Unagi and its ground has a very high level of energy.