All I can say is that so many people have tried what you are planning on doing and failed.
Just check out this guy on youtube.
He goes by the handle name of sexymdlman and he has some videos about his attempt to get a modeling career in Japan.
Only problem is that he went there with a tourist visa and although he had many offers, at the end he got nothing.
Sponsoring a visa is not free and it comes with lots of responsibilities and sometimes liabilities for companies so unless you are skilled labor in high need field such as engineering, you are out of luck.
You can still visit Japan and stay there for 90 days.
Here is the link to sexymdlman:
YouTube - sexymdlman's Channel