I received a question about how to order cheap tickets through Jetstar. (The 99 yen tickets, by the way, are gone – at least between Tokyo and Kumamoto but there are still relatively inexpensive seats available for some dates.) I went to the Jetstar website and found that the only way to find any tickets between Kumamoto and other points in Japan is to go to the Japanese website:
http://www.jetstar.com/jp/ja/home
I illustrated my feeling about this asymmetry between English and Japanese by adding a little comment to the screen shot I took of the English search page on the Jetstar site.