Two weeks is not very long for a job search- keep looking. Not many schools are going to give you a job quickly, you need to go through the usual hurdles. Showing up at the branches of large chains is not a good idea as recruiting is done centrally- follow their usual hiring process and you have a much better chance of finding a job. It very often takes two months or more to find a teaching job here.
Respond to the ads on the job sites and be prepared to wait.
You are not underqualified, you just need to realise that no school will hire you on the spot- Japan is very much a place where you have to follow the procedures, so that will be your best bet. Did Gaba give a reason for not hiring you?
The word for an English conversation school is ''eikaiwa'', rather than ''eikawana'', incidentally.
