Komatuna fonts are combined fonts that use Konatu and M+ fonts.

http://www.geocities.jp/ep3797/modified_fonts_01.html

I used these fonts for Komatuna:
Kanji = Konatu fonts
http://www.masuseki.com/?u=be/konatu.htm
Alphabet/Hiragana/Katakana, Full width alphabet = M+ fonts
http://mplus-fonts.sourceforge.jp/mplus-outline-fonts/index.html

THANKS TO
the authors of the fonts.

License
Konatu fonts, M+ fonts:
See docs-{konatu,mplus}.
fontforge-scripts:
Public Domain.

Author
UTUMI Hirosi <utuhiro78@yahoo.co.jp>

For developers:
If you want to generate Komatuna font manually,
run them:
$ cp mplus-1m-medium.ttf script-komatuna/
$ cp mplus-2m-medium.ttf script-komatuna/
$ cp KonatuTohaba.ttf script-komatuna/
$ cd script-komatuna/
$ ./fix-mplus-1m.pe
$ ./fix-mplus-2m.pe
$ ./import-mplus.pe

$ fontforge komatuna*.ttf
Element => Font Info => General
Set "Underline Position" to -80.

If you want to generate Komatuna-P font manually,
run them:
$ cp mplus-1c-medium.ttf script-komatuna/
$ cp mplus-2c-medium.ttf script-komatuna/
$ cp Konatu.ttf script-komatuna/
$ cd script-komatuna-p/
$ ./fix-mplus-1m.pe
$ ./fix-mplus-2m.pe
$ ./import-mplus.pe

$ fontforge komatuna*.ttf
Element => Font Info => General
Set "Underline Position" to -80.
