Mt. Kasuga is a primeval forest of ever-green broad leaf trees such as oak and beech which has been protected against logging as it is a sacred mountain. Within the forest are many gigantic trees more than 400 years old with trunks measuring more than 9m in circumference. It has been confirmed that the forest is the home to rare species such as forest green tree frogs and clouded salamanders. The entire forest is designated as a world heritage “cultural landscape”.