There area a couple of possible reasons for the high number of suicides. Seichō Matsumoto wrote a book in 1960 called Kuroi Kaiju (Black Sea of Trees) which describes the suicide of two lovers in Aokigahara, leading to romanticizing the act. Although, suicide is believed to have been associated with the forest long before the book was published. It is believed the 19th Century practice of "Ubasute" where an infirm or elderly female relative is carried to a mountain or desolate location and left to die by dehydration or starvation had more than once taken place there. Wataru Tsurumui’s controversial 1993 bestseller, The Complete Suicide Manual, describes various methods of suicide and even lists the forest as "the perfect place to die". Some who have committed suicide in the forest had been found with the book in their possession. However, there are those who think Japan's expectations of excellence may have something to do with it. Citizens who find themselves unable to succeed buckle under the pressure.
Then again, some remains found may not be from those who took their lives willingly. Supposedly, underground iron deposits cause compasses to go haywire and interfere with GPS devices, making it quite easy to get lost. Not only that, but the forest also contains cenotes, collapsed lava tubes, and hidden caves. Each can play their part in taking a life.
Either way, Aokigahara is not only associated with suicides but myth and ghosts as well. When Forestry workers come upon a body in the forest they carry it back to their station where a special room is designated for such occasions. In Japanese mythology, a corpse can not rest alone. If it is, the lonely, unsettled soul or Yurei will scream the whole night, and the body will move itself into the regular sleeping quarters.
Aokigahara is considered the most haunted location in Japan. Dubbed the "Purgatory of Yurei". Hikers have often seen apparitions as well as heard the howl of Yurei on the wind. Some have reported objects moving and seeing shadows amongst the trees. Spiritualists say that the trees themselves are filled with a malevolent energy, accumulated from decades of suicides. They try to prevent you from getting back out. They say if you look hard at the trees, you can see the faces of the dead in the bark.
Today, the forest is littered with colored tape used by walkers to find their way among the trees as well as discarded items and nooses, used to facilitate the suicide of its recent victims and bouquets of flowers left by grieving friends and family members.