Thanks again.
Now I am using not version 2.8 but 2.9. And current iTunes Producer Guide dose not shows that ibooks format in Japanese cannot be accepted.
Only one line "Do any languages require EPUB 3.0, iBooks 3.0 app, and iOS 6?" is there with language list including Japanese. Should we understand from only this sentence that we cannot use iBooks Author for Japanese to publish?
So far, there is no information iBook 3.0 app. The situation that our cmopany wasted precious time for couple of months is not being changed.
Additing one more, current iBooks Author 2.0 navicates automatically to use iTunes Producer after creating the delivery package without any caution and remarks. iTunes Producer is automatically run from iBooks Author by putting the button of Publishing.
This is quite strange for me. I don't want to say non productive words. However, I must say what is Apple?