Hōrai Mountain

Hōrai Mountain (宝来山, Hōraizan) is a legendary land of unknown location. According to mythology, one can not find the mountain nor the land where it exists if they search for it "as a human is able to", inferring that it is impossible to locate the mountain by conventional means. Because of this, there have been no definite reports of anybody having ever encountered the mountain and returned to tell of its existence nor its characteristics, leaving many to disregard Hōrai as mere folklore. However, it was agreed upon by many that chose to believe the stories that the Shinju was said to have grown at the base of Hōrai Mountain.

History
While the existence of the mountain remains shrouded in stories alone, there has been only a handful of accounts detailing successful journeys made to the mountain. Only those of the royal Ōtsutsuki were able to locate the mountain and subsequently the land where it existed, regularly making lonesome pilgrimages there as they believed it was a land which connected with the heavens. They happened upon a tree there, eventually being named as the Shinju (神樹, literally "god-tree"), and returned to their land with stories of this magnificent tree. It was worshiped as a "holy pillar" and the Ōtsutsuki King, whom made his journeys there, was often requested by his people to pray for their respective wishes. It is said that Princess Kaguya Ōtsutsuki, in search of the God-Tree's fruit which would grant her the power to end the ceaseless wars plaguing mankind, learned that while the tree was regarded as a deity, it had never been seen nor perceived by any human being; leading its existence to be classified as solely a myth. The story says that she was able to use her Byakugan, eyes that could perceive all things in the universe and a gift from the kami themselves, to find the mountain after years of traveling to lands unknown. The story goes on to say that Kaguya returned from this mountain, a "changed person", as she was originally held in regard as a bright and loving princess that cared for her people, but after returning from this land, she presented herself as tremendously wicked and coldly indifferent.

Kaguya's transmigrant, Seireitou Hyūga, had claimed to have visited the mountain after also spending most of his young adult years searching for it, following the death of his mentor, Shōyō Kawahiru. Though the authenticity of his claim is questionable, he had reported that the mountain carries a very frightening air about it and the experience did indeed change him.

Trivia

 * Mount Penglai (蓬萊山, Péngláishān), known in Japanese mythology by the name "Hōrai", was a legendary land in Chinese mythology which was said to be the base of the Eight Immortals. Many of the characteristics from this mythological land have been used on this rendition.