Ame No Sakahoko, the Upturned Sky spear, is a Hoko used by the twin Japanese gods Izanagi and Izanami to calm the chaos and create the land. It was later given to the God
Ninigi-No-Mikoto, who was sent to the land to become its ruler.
Ninigi No Mikoto, later stuck it on mount Takachiho, hiding it so that no one could use its powers for their own purposes.
It was first a relic of Japanese Mythology, which was broken In half due to the eruption of Mount Takachiho in 1913, the broken half was given as a gift to the Shimazu Samurai Clan.
The two pieces of The Ame no Sakahoko were transformed into incomplete artifacts by the residual mana in the atmosphere, like many ancient relics of the world.
It is said that the half of Ame no Sakahoko stuck on mount Takachiho selected a young Hiroto Mitsuki as its second master, the first being Sakamoto Ryōma when he first pulled it after trying to impress his wife during their honeymoon.
