The Japanese giant salamander is a species of fully aquatic giant salamander endemic to Japan, occurring across the western portion of the main island of Honshu, with smaller populations present on Shikoku and in northern Kyushu. With a length of up to 5 feet (1.5 m), it is the third-largest salamander in the world, only being surpassed by the very similar and closely related Chinese giant salamander and the South China giant salamander.

The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include some of the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two living families—the other being the Asiatic salamanders belonging to the family Hynobiidae—within the Cryptobranchoidea, one of two main divisions of living salamanders.