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Starer's Handbook in Japan トップページ
I think you have a terrific dream. One problem is that you will have to be an author/mangaka on the side while you do a job that will supply you with a work visa. Mangaka is a great career, but isn't one that people apply and are hired for. (Same with author and fashion designer). To live in Japan you will need a visa, and none of those careers will get you one. Something like teaching English is a more realistic approach to getting into Japan...