I have my eyes set on Japan when I'm out of collage?

This may be strange to you. I am 13, and for a year or two, I have been planning on going to Japan when I am out of collage. I even know some japanese. Like A, I, U, E O, and KA, KI, KU, KE, KO, etc. I know I'm so young and everything, but I'd say my mind is mature for my age. Anyway, there are so many things I want to know. Like how do you get to live in Japan if your an american? o you have to have visas and what not? Please explain for me. Sorry, and Arigatoo (Thank you) <-- See I know some xD