Red The Invasion of Hawai'i After Pearl Harbor (A Fictional History) by Richard Ziegler and Patrick M. Patterson. 2001 hardcover published by The Bess Press, Honolulu.
A very thoughtful book which gives a great deal of though about the long-term consequences of relatively small events. If Japan had taken Hawaii early in WW2 it is not really conceivable that the outcome of the war would have changed, but the history of Hawaii inevitable would have been different from the one we know.
This book gives excellent food for thought (pineapples?) about this different history of the isles. The recollections of three generations of Hawaiian-Japanese, newspaper-like reports and university lectures from the (different) future all together paint a picture that is entirely believable. Since all the events and policies described really happened in Japanese-occupied Asia they are probable too.
It could have happened if Japan had taken the isles. That it probably would not have happened as some reviewers complained is besides the point. History would not have happened as we know it, and Hawaii today would be different too. That is the point this book makes. And since the authors kept the book short and focused (no human interest stories, no steamy love scenes, no heroic/stupid politicians) it is utterly enjoyable. Alternative history at its best!