A day before tomorrow’s big announcement, Yodobashi Camera has released all the details along with the price.
pentax 645D
You can see the details on the Yodobashi website.
Body is 848,000 yen and a new 645 55mm lens is 100,000 yen.
Not sure on the release date at the moment.
The body and lens are also available at Amazon.co.jp here PENTAX 645D 
TRAVEL 67 : Chris Willson Photography 
The Pentax 645D is now available for pre-order on the Amazon Japan site with a release date of May 20th.