try this. pull, build, and in your ~/.config/vkdt/config.rc set
strgui/font:NotoSansJP-Regular.otf
or something similar (otf or ttf). if the filename after the : starts with a /, it’ll be interpreted as an absolute filename (see /usr/share/fonts/truetype/…). if not, it’ll look in the vkdt data/ directory. if the file doesn’t exist, it probably just crashes 
startup times suffer notably when loading a large font. certainly don’t want to make this a default for everybody.