man'yōgana

An ancient form of Japanese kana which uses Chinese characters to represent Japanese sounds. Their earliest attestation is not clear, but they seem to have been in use since at least the sixth century. The name man'yōgana is from the Man'yōshū (Anthology of Myriad Leaves), a Japanese poetry anthology from the Nara period written in man'yōgana. Man'yōgana uses kanji for their phonetic value, rather than their meaning. Several kanji could be used to represent the same sound, and in practice writers would often choose kanji with felicitous associations. Kanji used in man'yōgana eventually gave rise to hiragana and katakana. Hiragana developed from man'yōgana written in the highly cursive, flowing sōsho style; katakana is based on pieces of man'yōgana, and was developed by Buddhist monks as a form of shorthand. (from Wikipedia)