As an English teacher in Japan, you will either need an Instructor, Professor or the Specialist in Humanities/International Services visa (which is the one I have). I may have been wrong about the different requirements by country as it appears to be rather by profession. However I was not wrong about working holiday visas, those are deals arranged between countries. Take a look here for all those visa questions you have on your mind:
MOFA: A Guide to Japanese Visas - Documents to Be Submitted with Visa Applications