Switching your Ubuntu system to a Japanese keyboard layout allows you to type in Japanese using the Mozc input method. Depending on your setup, you may need to adjust both system settings and some configuration files to ensure the layout works correctly. Below is a step-by-step guide.

1. Enable Japanese Language Support in Ubuntu

1. Open Settings → Language Support.
2. Click Install / Remove Languages… and add Japanese.
3. Apply the changes and restart if necessary.

2. Reconfigure the Keyboard from the Command Line

If the layout still defaults to English, run the following in a terminal:

sudo dpkg-reconfigure keyboard-configuration

When prompted, select these options:

• Generic 105-key PC (intl.)
• Japanese → Japanese
• Use the default keyboard layout
• No compose key
• Yes to apply the changes

3. Configure Mozc for the Japanese Layout

By default, IBus Mozc may use a “default” layout instead of explicitly binding to jp. You need to update the configuration files.

Option A: System-wide Mozc XML

Edit the Mozc component file:

sudo vim /usr/share/ibus/component/mozc.xml

Find this line:

<layout>default</layout>

Replace it with:

<layout>jp</layout>

Save and restart IBus:

ibus restart

Option B: User Configuration (if XML does not contain <layout>)

In newer versions, the mozc.xml may look like this:

<component>
  <name>com.google.IBus.Mozc</name>
  ...
  <engines exec="/usr/lib/ibus-mozc/ibus-engine-mozc --xml" />
</component>

In this case, the layout is stored in a user configuration file. Edit:

vim ~/.config/mozc/ibus_config.textproto

Look for:

engines {
  name : "mozc-jp"
  longname : "Mozc"
  layout : "default"
}

Change layout : "default" to:

layout : "jp"

Then restart IBus:

ibus restart

4. Verify the Layout

1. Switch input method to Mozc (Japanese) using the system tray or keyboard shortcut.
2. Open a text editor and try typing — your keyboard should now follow the Japanese layout.

Final Notes

• If you are using a physical Japanese keyboard, this ensures keys match the printed layout.
• If you are using an English keyboard but typing in Japanese, you can still switch layouts virtually, but key positions may differ.
• Always restart IBus (or log out and log back in) after making configuration changes.