'male-body mountain',[2] also called Mount Futara (二荒山, Futāra-san)[2]) is a stratovolcano in the Nikkō National Park in Tochigi Prefecture, in central Honshū, the main island of Japan.

[4] Since its first known ascent by Buddhist monk Shōdō Shōnin in the 8th century AD, Mount Nantai has become a sacred mountain and a site of pilgrimage in Buddhism and Shinto.

In September 2008, the Japan Meteorological Agency was asked to reclassify Mount Nantai as "active" based upon work by Yasuo Ishizaki and colleagues of Toyama University showing evidence of an eruption approximately 7000 years ago.

[8]Archaeologists affirm that during the Yayoi period the most common go-shintai (御神体) (a yorishiro housing a kami) in the earliest Shinto shrines was a nearby mountain peak supplying with its streams water, and therefore life, to the plains below where people lived.

[5] The mountain not only provides water to the rice paddies below, but has the shape of the phallic stone rods found in pre-agricultural Jōmon sites.