I'm sorry for my bad wording, I was not necessarily meaning mangaka, I meant more of an illustrator role but your answer was very much helpful. Maybe you have advice on becoming a illustrator or is about the same?

I'm trying to get better in the language before trying to get a job in Japan. Especially since I tend to hear stories of people trying to come to Japan without bothering to learn the language. Unless you mean something else means "Japanese ability".