I haven’t been able to type Japanese because my database couldn’t handle it. The way to fix it is complicated, and requires hacking on the database directly, something that I wasn’t inclined to do (again; I have tried it a few times over the years).
Then it came to me, export then import the site! WordPress has wicked good import/export tools, and I have used them to merge other folks’ sites before. It really worked well, since I had three difficult things to do, and was able to do them with just a little DNS hackery.