Because there are many Mt. Shirane in Japan. This one is also called Kusatsu Shirane Mountain. It is the active volcano and there are many volcanic activities. The last eruption was 1983.
... is a caldera lake located on the top of Mt. Shirane. It is one of the popular spots in Mt. Shirane. It has the strongest acid water in the world.
There are many caldera lakes on this mountain.