A note about installation of Japanese layout on Pop_OS system.
Terminal:
sudo apt install ibus-mozc
Reboot (logging out then back in may be sufficient).
Settings>Region & Languages>Manage Installed Languages:
Under Install/Remove Languages, make sure Japanese is installed.
Make sure that “Keyboard input method system:” says “IBUS”.
Settings>Keyboard:
Add input sources (click on “+”). Under Japanese, you should be able to add “Japanese (Mozc).
Enjoy ⸜( ˊᵕˋ )⸝
