How to Fix Japanese Input Not Working on Ubuntu (Mozc, IBus, Fcitx Guide)

By 佐川 直弘 | Naohiro Sagawa (運営者)

※記事内に広告を含みます。Amazonアソシエイトとして適格販売により収入を得ています。　

1. Introduction

When using Ubuntu, you might run into issues such as “Japanese input doesn’t work” or “nothing happens when switching keyboards.” These problems are especially common right after installing Ubuntu for the first time or following a system update.

This article will help you identify the causes of Japanese input issues in Ubuntu and walk you through reliable methods to enable it. We’ll provide clear, step-by-step instructions so even beginners can follow along without confusion.

1.1 Why Can’t I Type in Japanese?

To type in Japanese on Ubuntu, you need special software called an IME (Input Method Editor). On Windows, you might be familiar with tools like “Microsoft IME” or “Google Japanese Input.” On Ubuntu, the most commonly used IMEs are Mozc and Fcitx.

However, Japanese input may stop working for several reasons, such as the following:

• The Japanese IME is not installed
• The IME is not properly configured (Mozc or Fcitx is not active)
• Incorrect keyboard switching settings
• Ubuntu updates reset your input settings
• Japanese input is disabled in specific apps like Chrome or VS Code

This article will guide you through fixing these issues one by one so you can type in Japanese smoothly.

1.2 What You’ll Be Able to Do After Reading

After reading this article, you’ll be able to:

• Enable Japanese input on Ubuntu reliably
• Set up Mozc or Fcitx properly for a comfortable typing experience
• Troubleshoot any problems that come up
• Switch between languages efficiently using keyboard shortcuts

This guide is designed for Ubuntu beginners, with simple instructions that don’t require technical knowledge. Just follow the steps, and you’ll be all set to type in Japanese.

2. Identifying the Cause of Japanese Input Issues

When Japanese input doesn’t work in Ubuntu, there can be several underlying reasons. However, they generally fall into one of the following four categories:

1. The Japanese input system (IME) is not installed
2. The IME is not configured correctly
3. The keyboard layout settings are incorrect
4. Japanese input is disabled in certain applications

Let’s go through each of these potential causes to pinpoint what’s preventing Japanese input from working on your system.

2.1 The IME Is Not Installed

To type in Japanese on Ubuntu, you need an input method editor (IME). In most environments, Mozc, a Japanese input system developed by Google, is commonly used.

How to Check

Run the following command to see if Mozc is installed:

dpkg -l | grep mozc

Example results:

• If you see something like ii ibus-mozc ... → Mozc is installed
• If nothing appears → Mozc is not installed and needs to be installed later

If Mozc is not installed, don’t worry—we’ll show you how to install it in a later section.

2.2 The IME Is Not Configured Correctly

Even if Mozc is installed, it won’t work unless it’s properly set up. On Ubuntu, IMEs are typically managed through an input method framework called IBus.

Check Current IME Settings

Run this command to check your current input engine:

ibus list-engine

Example results:

• If you see mozc in the list → Mozc is configured
• If you only see xkb:us::eng → Mozc may not be active or selected

If Mozc isn’t properly configured, the next section will show you how to fix it.

2.3 Incorrect Keyboard Layout Settings

If your keyboard layout settings are incorrect, you may not be able to toggle Japanese input at all.

How to Check Keyboard Layout

Use the following command to check your current keyboard layout:

setxkbmap -query

Example results:

layout: jp

This means you’re using a Japanese (JIS) keyboard.

layout: us

This means you’re using an English (US) keyboard.
If you’re actually using a Japanese keyboard but “us” is set, you may experience issues with character input. In that case, you’ll need to correct the setting.

2.4 Japanese Input Doesn’t Work in Specific Applications

If Japanese input works in some applications but not in others (like Google Chrome, VS Code, or LibreOffice), the issue may lie with the app itself.

How to Check

• Try Japanese input in another app (e.g., Text Editor or Terminal) to see if it works there.
• In Google Chrome, it’s possible that input works in the address bar but not on web pages.

For these app-specific cases, solutions will be provided later in the troubleshooting section.

3. How to Set Up the Japanese Input System

In the previous section, we identified the possible reasons why Japanese input might not be working. Now, let’s walk through how to properly set up Japanese input on Ubuntu.

The process involves the following three main steps:

1. Install Mozc (the Japanese input system)
2. Add Mozc as an input source
3. Configure and verify the input method

By following these steps in order, you’ll be able to get Japanese input working smoothly.

3.1 Install Mozc

Ubuntu’s default Japanese input method is Mozc. If it’s not already installed, you can add it by following the steps below.

1. Update Your System

First, update your package list and upgrade your system to the latest version:

sudo apt update && sudo apt upgrade -y

2. Install Mozc

Next, install the Mozc input method engine:

sudo apt install ibus-mozc -y

3. Verify Mozc Installation

Once installed, run the following command to confirm Mozc is properly installed:

dpkg -l | grep mozc

Example output:

ii  ibus-mozc   2.23.2815.102-1  amd64  Mozc engine for IBus

If you see output like this, it means Mozc was installed successfully.

3.2 Add Mozc as an Input Source

Once Mozc is installed, the next step is to add it to your system’s input sources.

1. Add Input Source via Settings

1. Open Settings
2. Select Region & Language
3. Click the “+” (Add) button under Input Sources
4. Select Japanese (Mozc) from the list and add it
5. Once added, make sure Mozc is prioritized as the default input method

2. Confirm Mozc Is Active via Terminal

Use this command to check if Mozc is set as the current input engine:

ibus list-engine

Expected output:

mozc

If you see “mozc” listed, then it’s correctly applied.

3. Restart IBus

To make sure your settings take effect, restart IBus with the following command:

ibus restart

3.3 How to Switch to Japanese Input

After adding Mozc to your input sources, let’s check how to toggle Japanese input.

1. Default Shortcut Keys for Switching Input

By default, you can switch to Japanese input using these keys:

• “Hankaku/Zenkaku” key (on Japanese keyboards)
• “Ctrl + Space” (on English keyboards)

If the Hankaku/Zenkaku key doesn’t work for toggling input, you’ll need to change the settings.

2. Change the Keyboard Shortcut

1. Open Settings
2. Go to Keyboard Shortcuts
3. Search for “Switch Input Method”
4. Change it to your preferred shortcut (e.g., Super + Space)

3.4 Confirm the IME Is Active

Let’s verify that the input method is now working correctly.

1. Check the Current IME via Terminal

ibus engine

Expected result:

mozc

If you see “mozc”, your Japanese input is active and functioning properly.

2. Test Japanese Input in a Text Editor

• Try typing in Gedit (Text Editor) or Terminal
• If you can type something like “あいうえお”, it’s working!

4. Alternative Japanese Input Systems Besides Mozc

While Mozc is the recommended Japanese input system for Ubuntu, in some cases you might want to use other IMEs (Input Method Editors) like Fcitx or Anthy.

Here are some situations where using an alternative IME might be helpful:

• Fcitx offers faster performance than Mozc on some systems
• Anthy allows Japanese input in environments where Mozc is unavailable
• Use as a backup if Mozc doesn’t work in certain applications

Let’s look at each IME, its key features, and how to install them.

4.1 Using Fcitx + Mozc

What Is Fcitx?

Fcitx (Flexible Input Method Framework) is an alternative input method framework. Like IBus, it supports Japanese input using Mozc, but it’s generally lighter and faster—especially on low-spec hardware.

How to Install Fcitx

1. First, install both Fcitx and Mozc:

sudo apt update
sudo apt install fcitx fcitx-mozc -y

2. Set Fcitx as your input method framework by updating the environment variables:

im-config -n fcitx

3. To apply the settings, either log out and log back in or reboot your system:

reboot

4. Check if Fcitx is active by running the following command:

echo $XMODIFIERS

Expected output:

@im=fcitx

If you see this, Fcitx is now enabled.

Configuring Fcitx with a GUI

1. Launch the Fcitx Configuration Tool (fcitx-config-gtk3)
2. Go to the Input Method tab and click Add
3. Add Mozc from the list
4. Move Mozc to the top of the priority list
5. Save your changes and restart Fcitx

fcitx restart

You’re now ready to use Mozc through Fcitx.

4.2 Using Anthy

What Is Anthy?

Anthy is another Japanese input engine. Although its conversion accuracy is lower than Mozc, it can be useful in minimal or restricted environments where Mozc cannot be installed.

How to Install Anthy

1. Install Anthy with the following command:

sudo apt install ibus-anthy -y

2. Go to Settings → Region & Language and add Japanese (Anthy) to your input sources
3. Restart the input method system to apply the change:

ibus restart

4. Switch to Japanese input and test if Anthy is working correctly

Although Anthy isn’t the best in terms of features or accuracy, it’s a lightweight fallback option when needed.

4.3 Comparing Mozc, Fcitx + Mozc, and Anthy

5. Troubleshooting (How to Fix Common Issues)

Even after setting up Japanese input on Ubuntu, it might not work as expected. If you’re still having problems, try the troubleshooting steps below.

5.1 Mozc Doesn’t Work or Won’t Input

If you’ve installed Mozc and added it as an input source but still can’t type in Japanese, try the following checks:

1. Confirm Mozc Is Installed

dpkg -l | grep mozc

If it’s not installed, reinstall it using:

sudo apt install --reinstall ibus-mozc -y

2. Check If Mozc Is Enabled

Use this command to see the current input engine:

ibus engine

Expected output:

mozc

If mozc is not shown, run the following to enable it manually:

ibus engine mozc

3. Restart the Input Method

If Mozc still doesn’t work, try restarting IBus:

ibus restart

Alternatively, you can reboot your PC to apply all changes.

5.2 Japanese Input Doesn’t Work in Specific Apps (Chrome, VS Code, etc.)

If Japanese input works in some apps but not others, try these fixes:

1. Google Chrome: Input Doesn’t Work on Web Pages

In Chrome, IME sometimes works in the address bar but fails on web pages.

• Fix: Disable hardware acceleration in Chrome:
  1. Open chrome://settings/ in the address bar
  2. Go to “Advanced” → “System”
  3. Toggle off “Use hardware acceleration when available”
  4. Restart Chrome

2. VS Code: Japanese Input Doesn’t Work

In Visual Studio Code, IME issues can be caused by accessibility settings.

• Fix: Update the following setting:
  1. Press Ctrl + Shift + P to open the Command Palette
  2. Search for Preferences: Configure Language Specific Settings...
  3. Set editor.accessibilitySupport to off
  4. Restart VS Code

5.3 Japanese Input Is Slow or Laggy

If typing in Japanese feels slow, you can speed things up by adjusting Mozc settings.

1. Open Mozc Settings

ibus-setup

Once the settings window opens, make the following changes:

• Disable “Predictive Suggestions”
• Disable “Learning Dictionary”
• Reduce the number of candidates displayed (e.g., 5)

These tweaks will lighten Mozc’s processing load and improve input speed.

5.4 Japanese Input Stops Working After Ubuntu Upgrade

Upgrading Ubuntu may reset your IME settings. Here’s how to restore them:

1. Reset IBus Settings

dconf reset -f /desktop/ibus/
ibus restart

2. Reinstall Mozc

sudo apt install --reinstall ibus-mozc -y

3. Check Environment Variables

Verify that the environment variables are correctly set:

echo $GTK_IM_MODULE
echo $QT_IM_MODULE
echo $XMODIFIERS

Expected output:

GTK_IM_MODULE=ibus
QT_IM_MODULE=ibus
XMODIFIERS=@im=ibus

If you see something else, correct them with:

export GTK_IM_MODULE=ibus
export QT_IM_MODULE=ibus
export XMODIFIERS=@im=ibus
ibus restart

5.5 Japanese Input Suddenly Stops Working

If Japanese input suddenly stops for no clear reason, restarting IBus and Mozc often resolves it.

1. Restart IBus

ibus restart

2. Manually Reactivate Mozc

ibus engine mozc

3. Reboot the PC

If the above doesn’t work, rebooting your PC usually solves temporary input issues.

6. FAQ (Frequently Asked Questions)

This section answers common questions about Japanese input not working or behaving inconsistently in Ubuntu. If the setup steps in previous sections didn’t help, check here for additional tips and solutions.

Q1. Japanese input suddenly stopped working. What should I do?

A:
First, try restarting the IBus input method with the following command:

ibus restart

If that doesn’t fix it, try re-enabling the Mozc engine:

ibus engine mozc

If the issue persists, reinstalling Mozc might help:

sudo apt install --reinstall ibus-mozc

Q2. How can I change the key used to switch to Japanese input?

A:
You can change the shortcut for switching input methods by following these steps:

1. Open Settings → Keyboard Shortcuts
2. Look for options like “Switch Input Method” or “Next Input Source”
3. Assign a custom key combination (e.g., Super + Space or Ctrl + Shift)

This lets you switch input more comfortably with keys that work best for you.

Q3. Japanese input doesn’t work in Chrome, but it works in other apps.

A:
This is often caused by Chrome’s hardware acceleration feature interfering with IME.

How to fix it:

1. Open Chrome and go to chrome://settings/
2. Scroll down to Advanced → System
3. Turn off “Use hardware acceleration when available”
4. Restart Chrome

This usually resolves Japanese input issues within Chrome pages.

Q4. Can I use Japanese input on Ubuntu running under WSL (Windows Subsystem for Linux)?

A:
You can’t use Japanese input directly in WSL’s terminal, since WSL doesn’t support native Linux GUIs by default. However, if you set up an X server like VcXsrv or X410 on Windows, you may be able to use IMEs in Linux GUI apps launched from WSL.

Keep in mind that this setup is complex, and WSL is mostly intended for CLI and English input.

Q5. Why aren’t conversion suggestions showing up when I type in Japanese?

A:
Mozc’s predictive suggestions or dictionary learning features may be disabled.

How to fix it:

1. Open Mozc settings by running the following in terminal:

ibus-setup

2. Go to the “General” tab
3. Make sure “Prediction” and “Learning Dictionary” are enabled
4. Click “OK” to save your settings

After restarting, conversion suggestions should appear normally when typing.

7. Summary and Additional Resources

This article provided a complete guide to solving Japanese input issues on Ubuntu. Let’s recap the key points and share some useful resources for further help.

7.1 Key Takeaways

To enable Japanese input on Ubuntu, follow these steps:

1. Identify the problem

• Check whether IMEs like Mozc or Fcitx are installed
• Verify that the IME is correctly configured
• Make sure the keyboard layout settings are accurate
• Check for app-specific issues in tools like Chrome or VS Code

1. Properly configure Mozc (the Japanese input system)

• Install ibus-mozc and add it to your input sources
• Run ibus restart to reload the input method framework
• Use shortcut keys like Hankaku/Zenkaku or Ctrl+Space to toggle input modes

1. Use alternative IMEs like Fcitx or Anthy if needed

• Fcitx is lightweight and performs well on low-end systems
• Anthy is useful when Mozc isn’t available

1. Apply troubleshooting techniques

• Use ibus restart or ibus engine mozc to restart the IME
• Disable Chrome’s hardware acceleration via chrome://settings/
• Reset IBus settings with dconf reset -f /desktop/ibus/ if necessary

1. Check the FAQ for quick solutions

• Fix sudden failures in Japanese input
• Adjust input method switching shortcuts
• Resolve issues specific to WSL or live USB environments
• Re-enable conversion suggestions if they’re missing

By following these steps, you can successfully enable and use Japanese input on Ubuntu with minimal hassle.

7.2 Additional Resources

If you need more information or want to stay up-to-date with the latest Ubuntu tips, check out these helpful resources:

• Ubuntu Official Documentation
  https://help.ubuntu.com/
• Ubuntu Japanese Forum (great for local Q&A and solutions)
  https://forums.ubuntulinux.jp/
• Mozc GitHub Repository (latest updates and development)
  https://github.com/google/mozc
• Fcitx Official Wiki
  https://fcitx-im.org/wiki/Fcitx
• Linux Tech Communities & Blogs
• Qiita (Japanese tech articles): https://qiita.com/tags/ubuntu
• Ask Ubuntu (English Q&A forum): https://askubuntu.com/

7.3 Final Thoughts

Setting up Japanese input on Ubuntu may feel a bit tricky at first, especially for beginners. But by following the clear steps in this guide, you should be able to overcome most challenges.

If you still encounter problems, don’t hesitate to ask for help on forums or Linux communities. Many users share similar experiences and can offer valuable advice.

We hope this guide helps you enjoy using Ubuntu with full Japanese input support—free from stress or frustration!