How many lakes are there in Japan?

It is hard to give an exact number, but as far as lakes larger than one square km are concerned, there are about 100 across the nation.
The largest is Lake Biwa.
Lake Biwa is one of the oldest freshwater lakes in the world.
It is believed that this lake dates back 5 million years.
It moved north from its original location in Mie Prefecture to Shiga Prefecture because of diastrophism or crust movement that occurred 1.2 million years ago.
The area of the lake is about 670 km2, which is far smaller than some of the larger lakes in the world such as Lake Superior (82,367 km2) and Lake Huron (59,570 km2),ｗhich span the area between Canada and the United States.