Is it possible to input Japanese lyrics on Linux?

lang:en

#1

Hello.
I’ve just installed Synthesizer V on Manjaro Linux and setting 3 voices up.
As I see the video https://www.youtube.com/watch?v=JyHrHVawpr4 , there are Japanese hiragana inputted.
But though I’ve set Japanese inputting system with fcitx-mozc, I can’t input Japanese to Synthesizer V.

Is it possible to input Japanese lyrics on Linux?
Best regards,
Aki42