I tested this on Gnome2 with Debian 7.0, but it should transfer over to other distros.
Step 0. (Optional) Setup Japanese Keyboard
From the Regional and Language Setup, click on the “+” and find your keyboard. In my case, it is a standard/boring Japanese 106 key keyboard.
Step 1. Install “ibus-anthy”
Open up a “terminal” and install “ibus-anthy”
$ sudo apt-get install ibus-anthy
Step 2. ibus setup
Again from the terminal, run “ibus-setup”.
Within ibus-setup, you will want to go to the second tab “Input Method”. From the drop down, select “Anthy” and add. The result should look like the screenshot:
Step 3. Test
Open up a terminal, gedit, etc. and make sure it works.
Issue 1. Cannot change between change and English
This will depend on the keyboard you have set and the keyboard shortcuts. To double-check this, open up the ibus setup.
Under the first tab “general”, you should see “keyboard shortcuts”, “enable or disable”. In my case, I can flip between Japanese and English with either “Control+Space” or “Zenkaku_Hankaku”.
Issue 2. Ibus is not starting on boot
Ibus should start automatically, but I have seen cases where ibus remains off. Two ways you can handle this (there are many more).
Solution 1. im-config
You can set the system to use ibus though the im-config. Just get im-config running and select ibus:
Solution 2. Startup Application
You can also create a startup item to get the ibus-daemon running.