The ebuild currently has LICENSE="as-is" which most likely is wrong. The tarball contains several README and LICENSE files which are all in Japanese. Please clarify under what terms this package can be distributed.
doc/ayu/README.txt: public domain doc/kappa/README: public domain doc/misaki/misakib8.txt: These fonts are free softwares. Unlimited permission is granted to use, copy, and distribute it, with or without modification, either commercially and noncommercially. doc/mplus/LICENSE_J: ditto doc/oradano/README.txt: You can distribute it with or without modification freely doc/shinonome/LICENSE: public domain
Thanks. I think we can summarise it as LICENSE="mplus-fonts public-domain".
Fixed.