Some pseudonyms have no Chinese characters;

Write hiragana or katakana directly for convenience or when you don't know how to write Chinese characters.

Japanese katakana is just a phonetic symbol. If you only look at the surface of the word, you can't know the specific meaning of the word at all. The Japanese make katakana for convenience. In fact, katakana is really convenient when introducing or translating foreign words from outside Japan. For example, the Japanese don't even need to translate English "drink" into "drinks/drinks", but directly translate it into the katakana word "ドリング" by transliteration according to the pronunciation of English (or foreign words). So theoretically, the number of Japanese katakana words can be said to be countless.

Some Japanese katakana words, because they have not been accepted by the Japanese public or recognized by people in the industry, may be doomed to be a flash in the pan in Japan's real life, which may include the following situations:

1) foreigner's name;

2) foreign place names;

3) Names of some Japanese or foreign companies;

4) Trademark names and brand names of Japanese domestic or foreign products;

5) Names of buildings in Japan or abroad;

6) Some Japanese like to write hiragana as katakana;

7) Others and so on.