Go to college. Take an exchange trip. Take the time to make contacts, in the welding industry or not. A japanese company likely won't hire a random kid, even if he's a plucky young lad with a "nothing is impossible!" attitude.
A) Shrink down to the size of an ant, or lift 6 times your body weight
B) "Get good at welding", then waltz through the border into a Japanese job
Do both, and you'll prove to me that "nothing is impossible."
And for a 10th grade American who can't speak Japanese and allegedly is poor at English - plenty of things are impossible.
Ask yourself, "Do I really think I can get a job in Japan just because I'm a welder?" If you answer yes, it's time to do some research and soul-searching. I should be rich because I'm handsome and funny, but the world doesn't work that way
Marine Corps Enlisted Job Descriptions -- 6043 -- Aircraft Welder + Okinawan post = Win
Protip: Last I checked, you don't go to college to become a welder. I have never heard of a welding college. Normally you take welding classes outside of school, at the end they give you a test, and companies will hire the best of the lot.
American companies.