http://mplus-fonts.osdn.jp/mplus-outline-fonts/design/index-en.html

They're really beautifully designed fonts, including proportional and fixed-halfwidth Latin, fixed-fullwidth Japanese character sets.

Most recent release is here: http://mplus-fonts.osdn.jp/cgi-bin/blosxom.cgi/mplus_fonts/mplus_fonts-141126-2.html

License is "free": http://mplus-fonts.osdn.jp/mplus-outline-fonts/index-en.html#license

Thanks!