Call of Cthulhu TRPG (Japanese edition): CTHULHU 2010 - BRP Japan Now
I found the TRPG section of my local bookstore. TRPG being Tabletalk Roleplaying Game to differentiate from RPG video games.
This is a Japanese supplement written by Japanese staff - making it FAR, FAR, FAR better than Secrets of Japan - which f-ing sucked (it is the only CoC book I've ever gotten rid of). 2010 includes Japanese mythos monsters that aren't Godzilla, a chapter on Japanese weapons, Japanese police, investigators, timeline, cults (Japan has tons), and Japanese adventures.
Slowly the translations will begin. Then there are other Japan focused CoC books to do... Cthulhu Cults Now, Cthulu to Teikoku (20s/30s Japan) and, wait for it: Hiezan Enjyo (Burning Mountain) a Sengoku period supplement. Deep ones and samurai... oh my.