Japan is a natural setting for Call of Cthulhu. It is a place absolutely festering with monsters, beasts, ghosts and horrors of every possible nature. Combined with a long history and an enigmatic culture, the possibilities for adventures in both modern and past times is boundless. And with Lovecraft's fear of what lies under the sea...why, any trip to a sushi restaurant could be a sanity shattering experience.
Michael Dziesinski has put together a tome. "Secrets of Japan" is a thick book, and the author was sure to pack in as much as possible from his considerable knowledge. The first section, Atmosphere, provides a crash-course in Japan both ancient and modern. Politics, social life, technology...everything you need to give your game the appropriate mood. Other sections detail more specifically game-orientated information, including secret societies and power groups, new skills, magic and characters. The final section contains some very short scenarios, and a collections of scenario ideas. Due to the depth of "Secrets of Japan", it would be great to see a companion volume of scenarios for those who don't really have the time to home-cook their own.
The format of the book also keeps in mind the various way people view Japan. He has a tongue in cheek comic strip running through the book called Cthulhu Sushi which is very funny. A certain giant green famous monster of filmland makes an appearance, although slightly altered. There is even a short section on running Call of Cthulhu anime-style, which made me do a sanity check when I read it.
However, for all of its excellence as a Call of Cthulhu game book, no one should mistake "Secrets of Japan" as anything like an authentic book on Japanese society and folklore. Although Dziesinski deeply mines the rich history of Japanese monster tales, he freely molds them to suit the game, something leaving little resembling the original beast other than the name. He also makes some mistakes in his Japanese translations, specifically in his section titles "Cultural Lexicon", where he attempts to show aspects of Japanese society using the language. This is no terrible error, however, as it doesn't affect game play in any way.