The first Japanese books were mainly written with the "Man'yōgana" system, a rebus-like transcription that phonetically uses kanji "Chinese characters" to represent Japanese phonemes. For instance, using Chinese "jiā" ( "add"), which was pronounced "ka" in Japanese, to write the Japanese mora "ka". Irregularities within this awkward system led Japanese scribes to develop phonetically regular syllabaries. In many cases, the new kana were graphic simplifications of Chinese characters. For instance, "ka" is written in hiragana and in katakana, both of which derive from the "Man'yōgana" 加 character.