These pseudonyms are borrowed from Chinese characters, and their meanings have been abandoned. They are a false usage, so they are called "pseudonyms". In Japanese, each pseudonym represents a syllable. Pseudonyms include unvoiced, voiced, semi-voiced and dial tone. In addition, there are syllables composed of two or three pseudonyms, namely, long sound, hurried sound and difficult sound.
Each pseudonym has two fonts, Hiragana and Katakana. Hiragana is generally used for writing and printing. Katakana is only used to record loanwords (words imported from other countries except China) and some special words. So now we use a orthographic calligraphy that uses ideographic Chinese characters and phonetic pseudonyms alternately. However, this orthographic calligraphy is too complicated and has become an important factor hindering the internationalization of Japanese.
Due to the great influence of China culture, more than 60% of Japanese words are borrowed from Chinese. According to statistics, there are about 2,400 Chinese characters in common use in Japan, which is 1000 fewer than China's Kangxi Dictionary.