You could ask the client to choose it, but they are particularly unlikely to have a license allowing them to share it. Japanese fonts can cost many thousands of dollars per license. At the same time, an anglophone isn’t likely to do a good job of picking the right font for a nuanced design context in Japan. (Would you leave English font choice to a Japanese-only speaker? Maybe comic sans, or Trajan, or Arial black...). Happily Japanese fonts are monospaced so changing the font later isn’t likely to mess up the layout.
Do do you and the client have typekit? A lot of Japanese fonts in there.