The M+ Fonts project provides a set of families with support for Japanese kana and over 5300 kanji glyphs, as well as many other languages and symbols.
Several versions of these fonts which are under different licenses (see below
for details) are available in third_party/Mplus.
You can preview M+ fonts via:
M+ Fonts are provided under a custom license:
These fonts are free software.
Unlimited permission is granted to use, copy, and distribute them, with or without modification, either commercially or noncommercially.
THESE FONTS ARE PROVIDED “AS IS” WITHOUT WARRANTY.
This license is prominently displayed on the project website (in both English and Japanese) and is also included in the downloaded release files, in both English and Japanese. At the time of this writing, the latest version is 1.063a.
Google Fonts created a modified version of M+ 1p font family and released it under the SIL Open Font License. At the time of this writing, the latest version is 1.061g.