Amenosakahoko (天逆鉾)
Amenosakahoko (also pronounced as Amanosakahoko) is a kind of halberd (hoko) which appears in the myths of medieval Japan. It is generally regarded as another name of Amenonuboko which appears in the Kojiki and Nihonshoki ("Records of Ancient Matters" and "Chronicles of Japan"), but the two halberds have different status properties. In Japan's medieval myths, it is also called 'Kongohousho' or 'Amanomagaeshi no hoko'. It is thrust into the summit of Mt. Takachiho-no-mine which stands between Miyazaki and Kagoshima Prefectures.
Changes in theories
Originally in the mythologies appearing in Records of Ancient Matters and Chronicles of Japan, the husband and wife deities Izanagi and Izanami, who were assigned with a job of completing the land formation, thrust Amenonuboko into the chaotic earth and stirred the earth with the halberd, and when they pulled the halberd up, a drop of the chaotic earth (or salt) which dripped from the point of the halberd turned into Onogoro Island (Kuni-umi; the birth of the land of Japan).
In the medieval period, however, this myth came to be interpreted in various different ways under the influence of Buddhism, causing changes in the characteristics of Amenonuboko.
"Yamato Katsuragi Hozan-ki", the Shinto book of Shugendo (Japanese ascetic and shamanistic practice in mountainous sites), explains that Amenonuboko is a mystical object generated at the time of tenchi-kaibyaku (creation of heaven and earth), which is an incarnation of Bonten (Brahma, a major Hindu deity thought to be responsible for creating the world), and that it is regarded as a vajra which has a power to smash the evil and has another name Amanomagaeshi no hoko. The Shinto book further explains that Ninigi, the sun goddess's grandson who descended to earth (Ninigi no mikoto in Chronicles of Japan), is a deity of a vajra or a mallet decorated with nu (gems), and that he is 天杵尊, also known as Kidoku-o, who has pacified the land using the mallet as a weapon.
"Tenchi Reiki Furoku", the Shinto book of Ryobu Shinto (a fusion of Shinto and Shingon sect of Buddhism), states that Amenosakahoko is the vajra which was stuck in Onogoro Island. Being influenced by these Shinto books, "Senguin Himon" describes that the grandson of the sun goddess descended from heaven carrying a sacred treasure, i.e., Amenonuboko. Based on these descriptions, it has come to be considered that Amenonuboko, that is Amenosakahoko, is on the ground.
Location
In terms of the location of Amenosakahoko, "Yamato Katsuragi Hozan-ki" states that 'Amanomagaeshi no hoko' is placed in the Sanctuary Takimatsuri-no-kami in Naiku (the Inner Shrine) of Ise Jingu (the Grand Shrines of Ise)
"Jinno-jitsuroku", the Shinto book of Ise Shinto (also known as Watarai Shinto; a school of Shinto teachings transmitted by priests of the Watarai clan at the Outer Shrine [Geku] of Ise Jingu), describes that Amenosakahoko is one of the sacred treasures belonging to Sarutahiko-jinja Shrine, and "Shinto Gobusho"(five-volume apologia of Shinto belonging to Ise Jingu) states that Amenosakahoko was thrown down from heaven by Amaterasu Omikami (the Sun Goddess) and is stored at the Sanctuary Misakadono in Ise Jingu's Naiku. In each of these statements, Amenosakahoko is described as being held in Ise Jingu. Incidentally, Chikafusa KITABATAKE (a Court noble of the Northern and Southern Dynasties) has concluded in his work "Jinno Shotoki" (A Chronicle of Gods and Sovereigns) that Amenosakahoko is placed in Hozan (which refers to Mt. Katsuragi in Nara Prefecture), that is, Onogoro Island.
Amanosakahoko in Takachiho
A tradition has been handed down, however, that Amenosakahoko was transferred from Okuninushi-no-kami to Ninigi who utilized it for the pacification of the land, and then thrust it in the ground of Mt. Takachiho-no-mine with a hope that it would never be used again.
The origin of this mallet is not known, but one theory holds that it already existed in the Nara period. Although no one had attempted to closely study this Amanosakahoko (perhaps because of a sense of awe) since the ancient times, there is an anecdote that Ryoma SAKAMOTO, one of the patriots in the closing days of the Tokugawa shogunate, was bold enough to pull it out when he visited Mt. Takachiho-no-mine. Ryoma wrote about this incident in his letter to his elder sister, and the letter is currently in the collection of the Sakamoto Ryoma Memorial Museum in Katsurahama (Kochi Prefecture).
Incidentally, Amenosakahoko which Ryoma pulled out was later broken by a volcanic eruption and one which exists now is a replica. While the hilt of the original halberd has been left in the ground, the blade, once retrieved and presented to the Shimazu clan, then dedicated to a shrine nearby, is now reported missing after passing into the possession of various people.
Sadakichi KITA (a historian of modern Japan) forms a conjecture that Sakahoko (a halberd placed upside down) was planted on the peak of Mt. Takachiho-no-mine by an ascetic Buddhist monk who, being prompted by "Jinno Shotoki" and the like, created the myth of the divine descent on Mt. Kirishima.
Oshiko-jinja Shrine in Takasago City, Hyogo Prefecture refers to Ishi-no-Hoden (the holy shrine of stone) existing in its precincts, Amenosakahoko and Kamigama (divine pots for making salt) in Okama-jinja Shrine (a subordinate shrine of Shiogama-jinja Shrine, Shiogama City, Miyagi Prefecture) as "Nihon San-ki" (Japan's three most curious items).