How to type Japanese characters on your Mac
Unlike many other languages, writing Japanese requires the use of special characters - Kanji, Hiragana and Katakana. This is relatively simple when writing with a pen & paper, but gets a bit tricky when it comes to typing on a computer. Virtually all computer keyboards use Roman characters, and while you can type Japanese using Romaji, there may be cases where you want to type in proper Japanese. Typing Kana characters on your Mac using your Roman keyboard is possible, however it requires you to switch your keyboard language and interprent the Kana using Roman characters. So read on to find out how to do so!
The first thing you're going to have to do is change your Mac's keyboard language. To do so, open the System Preferences and click on the "Language & Region" pane. You will then have to add "Japanese" to the preferred languages pane on the left-hand side, as per the screenshot below.
Now click on the "Keyboard Preferences" button and in the "Input Modes" section of the screen that comes up make sure that Katakana is ticked as well as Hiragana.
Now that you've enabled Hiragana and Katakana, you can make either one your "typing language" at any time. To do so simply go up to the top menu-bar, click on the flag symbol and select either Hiragana or Katakana from the resulting list.
Hiragana and Katakana are relatively straightforward to type - All you need to do is select Hiragana/Katakana in the menu shown above, then type the Romaji for the Kana you want to enter. For example, if you wanted to type "ありがとう", you'd select Hiragana from the menu, then type "arigatou". As you type Mac OSX will spell out each sound in Hiragana on the fly, seeing as it's faster for most people to type the Romaji and have it converted than dedicate a key to every character. Same works for Katakana.
If you would prefer it is also possible to select the Hiragana and Katakana characters from a table rather than typing the roman characters out. To do this simply select "Type using Kana table" from the language drop-down menu and the table of Kana characters will appear. Then you can simply press each character on the table and it will appear in the selected text field.
Kanji is a little more complicated, though. Because a Kanji character does not represent a single sound, you must type out the sound of the character in Hiragana or Katakana, then choose from a list of Kanji combinations. For example, if I wanted to type "日本" I'd have to type "nihon", which Mac OSX would automatically convert to "にほn" (or "ニホn" if you're using Katakana), then hit the down arrow, followed by the enter key (to select the second option on the list, which is "日本") to get "日本". It does sound complicated, but be assured that you'll soon become fast at it!