CTAN has a new package: ptex
pTeX is a TeX system by ASCII Co. Ltd. in BSD license which can handle Japanese in good quality so that the output can be used for commercial publishing purpose. It requires and conform itself to teTeX.
This package is located at http://tug.ctan.org/tex-archive/language/japanese/ptex . More information is at http://tug.ctan.org/pkg/ptex (if the package is new it may take a day for that information to appear). We are supported by the TeX Users Group http://www.tug.org . Please join a users group; see http://www.tug.org/usergroups.html .
ptex – A TeX system for publishing in Japanese
PTeX adds features related to vertical writing, and deals with other problems in typesetting Japanese. A set of additions to a TEXMF tree, for use with PTeX, may be found in package PTeX-texmf.
PTeX is distributed as WEB change files.