These ebuilds come from http://ebuild.gentoo.gr.jp/.
If you have some problems, go to the official site first.
nzmath : number theory oriented calculation system built on Python ( http://tnt.math.metro-u.ac.jp/nzmath/ )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a gentoojp
For Paludis use this rsync : rsync://gentoo.zugaina.org/gentoojp-portage
If you have a problem : ycarus(-at-)zugaina.org