The park has a large mixed group of snow monkeys or Japanese macaques.
It is the most northerly living non-human primate.
Their thick coats help them survive winter temperatures of -15C.
However, they are most well-known for the habit of sitting in natural hot springs to escape the winter cold.
Japanese macaques feature prominently in the religion, folklore and art of Japan, as well as in a number of proverbs.
There are estimated to be around 114,341 Japanese macaques in the world, with most of them on the Japanese islands Honshu, Shikoku and Kyushu.