Aokigahara, also known as the Sea of Trees , is a forest on the northwestern flank of Mount Fuji on the island of Honshu in Japan, thriving on 30 square kilometres (12 sq mi) of hardened lava laid down by the last major eruption of Mount Fuji in 864 CE. The western edge of Aokigahara, where there are several caves that fill with ice in winter, is a popular destination for tourists and school trips. Parts of Aokigahara are very dense, and the porous lava rock absorbs sound, contributing to a sense of solitude that some visitors attribute to the forest.

Mount Fuji is an active stratovolcano located on the Japanese island of Honshu, with a summit elevation of 3,776.24 m. It is the tallest mountain in Japan, the second-highest volcano located on an island in Asia, and seventh-highest peak of an island on Earth. Mount Fuji last erupted from 1707 to 1708. The mountain is located about 100 km (62 mi) southwest of Tokyo and is visible from the Japanese capital on clear days. Mount Fuji's exceptionally symmetrical cone, which is covered in snow for about five months of the year, is commonly used as a cultural icon of Japan and is frequently depicted in art and photography, as well as visited by sightseers, hikers and mountain climbers.