ref: 68d9155e1fff6c4c2d69c96f3fd4e7dc66cdeebd
dir: /sys/src/cmd/aux/mnihongo/README/
mnihongo is a fairly clumsy troff post-processor that catches unicode characters that might be japanese, looks them up in a font file (currently /lib/font/bit/pelm/unicode.9x24.font) to get the bits, converts that to postscript, and dumps that in the output. Widths are taken from troff font Jp, which has at best a simple approximation to the truth. The program itself is normally called implicitly by loading the troff macro package -mnihongo, which does a .pi command.