Sorry to hear about that. If you will permit the ridiculous comparison of you to a piece of cake, it may simply be that they got to your application at the end of a long meal, and simply did not have any more space for cake. In other words, while I am not sure when you submitted your application, right now is probably the hardest time to come over, because most schools and Boards of Educations have already finalized their teacher lists for the school year which starts in just under two weeks. It might not be anything about you as a person, but rather that your application came after everything filled up. Always worth applying again!
As you said, they do not tell you why the reject applicants. Anything I or anyone says will be probably be a bit of a shot in the dark, but based on what you wrote, there is one thing that stuck out to me.
I am pretty certain that the majority of Interac ALTs do not get placed in cities like Tokyo and Osaka. Most people, like I did back when I was with them, got send out to the sticks. Competition for those big city spots is fierce, as many people aren't all too familiar with the Japan outside of Tokyo/Osaka/Kyoto, similar to how most Japanese citizens only know a few main cities in the United States.
While there is fairly large turnover in any ALT company, the company loses time and money with people that don't make it a year, or leave after one year (training, orientation, etc.). So, they are most likely looking for people who are more flexible with their location preference, and isn't really focused in on one or two locations.
I don't even know if this came up in your interview, but it will help in future interviews to show interest in Japan as a country, not Japan as Tokyo. If you didn't talk about Tokyo, great, but if you did, it may be helpful to talk about your interest in the country, wherever you go. It will show flexibility and reasonableness on your part, and make you a more attractive candidate.
Hope this helps!
Lastly, again, this is complete speculation on my part, but my guess is that they want people who are interested/like Japan, not love Japan. For the vast majority of people, I'd say Japan is no better or worse than many developed nations. In other words, for all the wonderful things here, there are just as many problems or negatives. I have been here for over ten years, and while I enjoy living here, if I had to list all the problems I have or the country has, I could come up with just as large a list as I could for the US, my home.
I think this ties in a bit with the Tokyo v. rest of Japan thing, but if you show too much interest in a relatively small slice of the country, the might worry that you will become disappointed/disillusioned in the highly likely scenario that you are stationed in the other 99% of the country. Not satisfied -> wish you could be in Tokyo -> quit work -> they have to find someone else.
So, in short, show a balanced interest in Japan and a willingness to be flexible with what you are met with, and your chances at finding something will surely go up.
Good luck!
