A loophole in japan working visa?

I have 4-year finance university degree. It can get me a humanities working visa. But I'm planning to use next 4 years to learn N1 Japanese and digital painting to get a Game/2D concept designer work. This job is in International services. Since all of them are under a same visa category now, can I get hired and use my finance degree to get a working visa and work as game concept artist/ designer? Or I must get 3 years of experience. English teacher is under International services too and everybody can get working visa with any major 4-year degree. I wonder if I can do the same for any jobs in International services visa. If cannot, is it wiser to work for another 3 years to get alternative requirement or come to Japan and learn 4-year degree in Illustration/Design? Assume after 4 years of self studying I will have N1 and good enough portfolio to get hired.

You need 3 years experience.