Tankoubon, or better known as Graphic Novels, compile manga chapters into book format. Below you can find release date information as well as ISBN numbers to help you track down a copy of your own. Because of the long time gap between the release of volume two and volume three, it was decided to re-release the first two volumes. Appare Jipangu has not been released in English.
Bunko, or pocket editions, are smaller versions of the tankoubon. They compress the series into a smaller amount of volumes, to make it easier for new readers to collect. Bunko have no extras like the authors comments, or extra illustrations that the tankoubon have. Its just the manga, nothing more, nothing less.