To find where the font files are stored in the system, use the following command line
fc-list | grep
For example:
# fc-list | grep '游明朝'
/home/transang/.local/share/fonts/Mincho/Yu Mincho Demibold.ttf: Yu Mincho,游明朝,Yu Mincho Demibold,游明朝 Demibold:style=Demibold,Bold
/home/transang/.local/share/fonts/Mincho/