Go into the actual files of the game. If you're using the itch desktop app you can click the cog symbol next to "Launch", and then press "Manage", and then "Open folder in explorer".
Next go to Template > Font. In Font there should be "VL-Gothic-Regular" and "VL-PGothic-Regular". Open these files, and press the "Install" button on the top left. Make sure you install both of them.