Set up a Japanese input source on Mac
If you set up the Hiragana, Katakana, or Romaji input mode, you can type in Japanese.
On your Mac, choose Apple menu > System Preferences, click Keyboard, then click Input Sources.
Click the Add button , select Japanese (on the left), then select any of the following:
Japanese - Kana
Japanese - Romaji
Tip: The Romaji typing method is useful when you’re not using a Japanese keyboard; text you type is automatically converted to hiragana.
After you add a Japanese input source, you can change preferences, for example, to select input modes or show predictive text completion candidates.