Probably the most popular and the easiest job for foreigners to get in Japan is teaching English.
Lots of links on this site to schools looking for teachers.
Usually a degree (in any field) is required.

Interested in hearing from people who have worked for an English school in Japan.
Please tell us here about what those schools were like to work for...

Anyone know about the teaching group called "Happy Sensei" from the website of the same name?
Good or bad?

Never heard of them...

But about teaching English in Japan I want to say that I think it is any easy way to get a visa, get sponsorship and get into Japan.. we can then find another job and company if we want to, cant we??

Sure!
Many people use that strategy to get in, get settled and then find something else.

Exactly what I did

Thought this info on the Japanese Exchange Teaching program might be useful:

"Each year the JET Programme, with the aid of the Japanese Ministry of Foreign Affairs, recruits thousands of new participants to come to Japan and experience a new and unique way of life. Participants are assigned to be either Assistant Language Teachers (ALTs) who provide language instruction in elementary, junior and senior high schools; Coordinators for International Relations (CIRs) who work in communities on international exchange activities; or Sports Exchange Advisors (SEAs) who promote international exchange through sports.

Participants are placed with local government organisations throughout Japan in every imaginable locality, including large cities, small and medium-sized towns, and rural farming and fishing villages."

If you want any more info on it please let me know