Amazon.com has this posted on the page for the ebook edition of The Monster Movie Fan's Guide To Japan:
Why would you need a Kindle app? It is because of the formatting of some ebooks. Not all ebook formats are compatible with existing software.
I found out a few years ago that some devices will not properly display Kindle-formatted ebooks. Before purchasing a Kindle-formatted ebook, people need to find out if their browser, software, app or programs are compatible with the various ebooks so that they render correctly. One digital size does not fit all.
One fellow complained that the ebook was "unreadable" in his device (whatever that was). I checked with other people that obtained the ebook and they all said it looked fine to them. So it obviously wasn't compatible with the device he was using.
Since then, I have cautioned people to check their browser, software, app or other programs to make sure that the Kindle program is compatible before purchasing. I have received no complaints since.
Amazon.com is making it easier by providing a FREE Kindle app! Go here to get it and The Monster Movie Fan's Guide To Japan ebook!