While the true landscape of the Moon remains somewhat unknown, one can easily see that the rock suspended in the sky bears a striking golden color, not unlike the color of its people's hair. Many craters dot the surface, giving a small bit of insight as to what events have transpired there. From Nippon, no remnants of the former civilization can be seen, but it is also unknown as to whether ruins and rubble even remain, having been so long since the people of the moon disappeared.
Long, long ago, perhaps even before records existed, the Moon was the home of its golden-haired Moon Tribe and the center of activity of its people. The race living on this distant rock developed incredibly technologies, such as portals for time travel; computer-like devices, not unlike the ones used by the Tao Troopers; and a massive ship intentioned for spaceflight. However, an unknown catastrophe struck the land and wiped out all of its people, except three: Kaguya, Waka, and Sugawara.
Kaguya, a young child at the time, was placed safely into a rocket and landed in the bamboo forests of Sasa Sanctuary, where she would be found and cared for by her adoptive parents. Waka stole away in the steel ship that is the Ark of Yamato and made his way to the Celestial Plain. Once there, Waka met up with Amaterasu and was permitted to dwell alongside her and her people. How Sugawara escaped is unknown.
After Kaguya is captured by a possessed Emperor Takara, she reflects upon her past and recalls a faint memory from her early childhood. Determined to explore her past, she traces her memories back to the same bamboo forest she has known her whole life, having been there many times to help her grandfather, Mr. Bamboo cut down the mighty stalks for use in his crafts. Alongside Amaterasu, Kaguya unearths the rocket she fell to earth in. Beginning to understand her origins, Kaguya takes it upon herself to find out who her true people are and where she came from. With a warm final embrace, Kaguya leaves behind her adopted grandfather and begins her trek to the Moon. However, she is never heard from again.
The Moon of Nippon, while bearing much resemblance to the moon of our own world, goes on to serve a second purpose. In Shintō mythology, one of the few kami noted to be evil are Tsukuyomi, god of the moon. Angry at the food goddess Ukemochi for the manner in which she produced a meal for him, he murdered her in a rage, causing the goddess of the sun, Amaterasu, to refuse to share a place with him in the sky. This dispute eternally separated day into night, as it appears in the game. However, this goes even further as to suggest a more wicked nature for both the lunar realm itself and its people in the world of Ōkami.