The forest area is 30 square kilometers. Its base is hardened lava formed after the eruption of the Nagao parasitic crater belonging to the Fuji stratovolcano (a small cone on the slope of the large main cone), which took place in 864 (Great Jogan Eruption).
Over 1200 years, a virgin forest was created in the lava area, consisting mainly of conifers (Japanese pines, red pines, cypresses) and deciduous trees (Quercus crispula). This forest is considered pristine and has remained untouched by humans. The trees are abundantly covered with moss.
Visually, the forest seems larger than its surface suggests, because the area is characterized by a very high density of trees. The forest is very quiet and there is no wind.
