A possible oldest example of Man'yōgana is the iron Inariyama Sword that was excavated at the Inariyama Kofun in 1968. In 1978, X-ray analysis revealed a gold-inlaid inscription consisting of more than 115 Chinese characters and this text, written in Chinese, included Japanese personal names which were supposedly phonetically written. This sword is thought to have been made in the year 辛亥年 (471 A.D. in commonly accepted theory), and analysis of the rust on the sword implies that the metal used may have been refined from magnetite found in the eastern region of China, imported into Japan, and used to forge the sword there. There is a possibility that the inscription of Inariyama sword is written in a version of the Chinese language used by some ancient Koreans.
Man'yōgana uses kanji characters for their phonetic[a] rather than semantic[b] qualities—in other words, they are used for their sounds and not their meanings. There was no standard system for choice of kanji; different kanji could represent a similar sound, the choice made on the whims of the writer. By the end of the 8th century, 970 kanji were in use to represent the 90 morae of Japanese. For example, the Man'yōshū poem 17/4025 was written as follows:
Hakuhi no umi
The sounds mo (母, 毛) and shi (之, 思) are written with multiple characters. While all particles and most words are represented phonetically (多太tada, 安佐asa), the words umi (海) and funekaji (船梶) are rendered semantically.
In some cases, specific syllables in particular words are consistently represented by specific characters. This usage is known as Jōdai Tokushu Kanazukai. It has led historical linguists to conclude that certain sounds in Old Japanese, represented by differing sets of man'yōgana characters, may have merged since then.
Kanji that were used as man'yōgana eventually gave rise to hiragana and katakana. Hiragana developed from man'yōgana written in the highly cursivesōsho style; katakana is based upon man'yōgana, and was developed by Buddhist monks as a form of shorthand. In some cases, one man'yōgana character for a given syllable gave rise to the current hiragana equivalent, and a different one gave rise to the current katakana equivalent. For example, the hiragana る (ru) is derived from the man'yōgana留, the katakana ル (ru) is derived from the man'yōgana流.
The use of multiple kanji for a single syllable also led to hentaigana (変体仮名), alternate letterforms for hiragana. Hentaigana were officially discouraged in 1900.
Man'yōgana continues to appear in some regional names of present-day Japan, especially in Kyūshū. A phenomenon similar to man'yōgana, called ateji (当て字), still occurs, where words (including loanwords) are spelled out using kanji for their phonetic value: for example, 倶楽部 (kurabu, club), or 珈琲 (kōhii, coffee).
Katakana with man'yōgana equivalents (segments of man'yōgana adapted into katakana highlighted)
including obsolete syllabograms
^Sacred texts and buried treasures: issues in the historical archaeology of ancient Japan by William Wayne Farris P102  "it seems likely that the Korean organization to provide tribute to the ruler would have been influential with the Yamato king as well. To be sure, the Korean model may have harked back to Chinese example"