[MMM]

I am going to assume you want to a published comic artist in Japan.

That's a little like saying "I want to be a successful rock musician. What degree do I need?"

It doesn't quite work like that. Unlike many other careers, a comics artist isn't hired for a job as much as commissioned for a project. You are not hired based on what degree you have or where you studied, but how talented you are. Your portfolio will open doors, not your resume.