Hi, since I have been working as an English teacher, I thought I might give you some suggestions.
First, there are several ways to teach English in Japan.
1: JET program - teaching at public schools
2: Working in English conversation schools like ECC, GEOS ro AEON.
I guess the above doesn't match your demand since you are looking for a job which you can do for a long time.
It is difficult to get a lifetime work as an English teacher in Japan.
Another way is that
3: Opening your own English school - most of people get married to Japanese
4: Teaching English at university - I am not sure what qualification you need.
I think you should contact uni which have many English corses, like Kansai Gaidai uni or :Tokyo University of Foreign Studies,
but if you would like to work in Kanazawa, probably Kanazawa uni would be nice
http://www.kanazawa-u.ac.jp/e/Kanazawa is a nice place to live, but there aren't many unis. Some vocational school or college(senmon-gakko) might be nice too.
It depends on what kind of thing you would like to teach.
I recommend checking with schools in Japan directly. Personaly, I would work at uni or try working as JET and then work in English school then open own school. Experience and patience are needed to teach English :)