It seems almost impossible to land a non-English teaching job from scratch. Almost all the jobs I see are either: not sponsoring visas, require Native/Business-Japanese level, or worse, NOT entry level. Like what was said before, best option seems to be: go to Japan one way or the other and make connections.
Well, that's also true for any other country I suppose (I speak only for the US). Connections make or break here. Allows you to bypass hundreds of competition with just one good referral.