Katakamuna is an ancient civilization, a moji script, a science of the universe. This post contains information from Japanese sources in a book and on the Internet.
Part 1 Katakamuna Civilization and Documents
From http://ejje.weblio.jp/sentence/content/katakamuna, whose entries come from Japanese Wikipedia.
Katakamuna civilization is a super ancient civilization that is said to have existed in Japan. カタカムナ文明とは、かつて日本に存在したとされる超古代文明。
Katakamuna civilization is said to have existed at the end of the paleolithic period (Japan) before the Jomon period. 縄文時代以前、旧石器時代(日本)末期に存在したとされる。
NARASAKI Kogetsu was the first to advocate the existence of the Katakamuna civilization in Japan. 日本で初めてカタカムナ文明の存在を唱えたのは楢崎皐月（ならさき・こうげつ）である。
According to the Katakamuna documents, it is assumed that the civilization had highly sophisticated technology and an original system of philosophy. 極めて高度な科学技術や独自の哲学体系を持っていたことがカタカムナ文献から推測される。
It [these documents] is so called because the Katakamuna characters were used. カタカムナ文字を使用していたとされる事から呼ばれる。
Later, Kogetsu succeeded in deciphering this document (commonly called “Katakamuna documents”) over five years.
These characters were called “Katakamuna characters” from the location where they were enshrined and “Katakamuna Civilization” was advocated as the civilization in which the characters were used. この文字はそれが祀られていたとされる場所の名から「カタカムナ文字」と呼ばれ、その文字を使用していた文明として「カタカムナ文明」が提唱されたのである。
Part 2 Fukano Kazuyuki, Chogakusho Katakamuna no Nazo, 超科学書「カタカムナ」の謎, Kosaido Books, 1993
NARASAKI Kougetsu (楢崎皐月), born 1899, was a scientist who studied at Japan Electronic Engineering School. In the 1920s he was in Manchuria where he invented a special oil that blocks electricity and developed a man-made gasoline; he was in the Japanese Army that was making iron in Manchuria. After he came back, he worked in a medical company where he had a project to raise farming yields by use of electricity. So he was putting up power lines in Hyogo-ken’s Kincho-zanchu in the Rokkousan 六甲山 mountain range. He wanted to learn why a large matsu pine could grow on top of an iwa large stone. He spent five years living in the wild and this experience resulted in his writing a book. Moreover, it resulted in his discovery of Katakamuna.
This is a book about Katakamuna, a super-science from a super-ancient civilization. The information comes from a scroll which Narasaki copied over a period of twenty days in 1949. Narasaki was studying the environment when a hunter, around 50-60 years old, appeared holding a gun. The hunter told Narasaki that the power lines were preventing animals from drinking from lakes, so Narasaki stopped doing that. In gratitude, the hunter came back and said that his father was guji at Katakamuna Jinja. He brought a makimono that he said is their goshintai, written in strange moji. He allowed Narasaki to copy the document. The document had been protected by the Hira-Ke and Meshi-Ke families.
By a strange coincidence, Narasaki had studied in Manchurian temples with Taoist elders. They told him that there was once in Japan a zoku, tribe, of people called Ashiya, a civilization with a high technology. They had yatakagami writing and special iron for making steel as well as a high level of culture. Their culture came to China through the Chinese Shinoushi who brought from Japan what would be the beginning of Chinese culture.
Katakamuna comes from the early Jomon at the end of the ice age more than 10,000 years ago.
There are 80 uta in the Katakamuna document that Narasaki copied out in 1949. Five out of 80 were published in Narasaki’s jisho. There are other uta in this Fukano book; they were written by Narasaki, who spent five years studying the document.
This is how Fusano explains Katakamuna.
Kata = seen world, the world of form
Kamu = unseen world
Na = nushi, lord
Thus, Kata-kamu-na is the lord of the seen and unseen worlds. A Katakamuna-jin has knowledge of the unseen world behind the world of form.
Everything comes from Ama. Uchu is everything, the universe. Mari is an atom of matter. Ama creates everything, and it comes from the unseen world, Kamu-no-sekai.
Tennen, everything, is made of 8 different rasen-no-kaiten spirals or junkai circular movements and opposite movements.
Katakamuna includes the super-micro and super-macro of joukyo appearance. Seimei no honjitsu, life and mind and uchu universe. Seibetsu living organisms occur naturally, and all things have life.
In Narasaki’s book, there are 80 uta arranged in spirals with three types of symbols in the center: Yatakagami symbol in 71 spirals, Futomani in 7, Mikumari in 2 spirals. The illustration shows the Yatakagami symbol in the center of one of the uta.
The first uta reads:
katakamuna – hibiki – mano suheshi – ashia touan – utsushi – matsuri.
Katakamuna – sound – mano suheshi? – Ashia Touan – wrote this – made offering in matsuri.
Start reading from the center and spiral out. It seems to say that Ashia Touan received the message of Katakamuna from somewhere and he wrote it down and made an offering in matsuri.
Katakamuna reveals konpongen principles of: Universe, tennen, and shizen This is something like the Universe, Heaven-and-Earth, and Nature.
The first uta is telling about basic principles of everything in the seen world. The Unseen world has limitless energy, Kamu and the lord of Kamu. The Seen world is made from the Unseen world, Amana is the lord of Amana. Everything we have here is Kamuna and Amana vibration; tougou integration of Amana and Kamuna.
Here are verses 5 and 6. Below them are shown the three types of centers: Yatakakami, Futomani, and Mikumari.