Fcitx [ˈfaɪtɪks] is an input method framework with extension support. Currently it supports Linux and Unix systems like freebsd. It has three built-in Input Method Engine, Pinyin, QuWei and Table-based input methods.

Fcitx tries to provide a native feeling under all desktop as well as a light weight core. You can easily customize it to fit your requirements.

To install it, pull up a terminal and install the japanese fcitx input module and a japanese font of your choice, i picked noto-font-cjk:

yay -S noto-font-cjk fcitx5-mozc

Configure fcitx-configtool so you can switch between your input languages (if you use dwm it will open up a text file):

In case you have dwm, you need to uncommend a specific line, it should now look something like:

[Hotkeys]
TriggerKey=CTRL_SPACE

After the installation you need to configure fcitx in your .xprofile, which means your system enviroment so that your system accepts fcitx as standard input:

export GTK_IM_MODULE=fcitx 
export QT_IM_MODULE=fcitx 
export XMODIFIERS=@im=fcitx

Reboot your system so that it takes effect.