Peabody is stil working on it. There is some mods out there that bring the IJN to the battle. Keltos1`s japanese submarines are a great place to begin
http://www.subsim.com/radioroom/showthread.php?t=137761
Others are working on some diffrent mods that are focusing on the IJN. I am working on a Takao surface mod based on peabodys and keltos1`s work....
TBear