We are adding the modules we have built over the years, the ones that look reasonably general-purpose, to Odoo's Apps page. The modules themselves have always been public on GitHub, but getting them onto Odoo's page had fallen behind. (We used to link a Launchpad repository, and after the upheaval of the move to GitHub the job kept being put off.)
There are not many yet, but they can be downloaded here, and we would be glad of your feedback on anything you notice once you have tried them. There is nothing for v9 yet; that will come in time.
As things stand there is no Japanese description, and the English is kept to a minimum, so it will be hard to picture concretely what each one is for — but ask us and we will gladly explain.
Our community modules are now on Odoo Apps