How to begin preps for future?

I'm currently in high school at the end of summer break, so I'll be a senior in a few weeks. I've self studied Japanese for about two years and can hold a short conversation. My ideal job is a Japanese to English translator or English teacher who lives in Japan.
I'd love nothing more than to do an exchange or JET like program in the future but as for exchanges, I'm extremely low income. I do quite well academically. I learned recently that you can't gain a work visa in Japan without a bachelors degree, and for JET-like programs pretty much need to be in college. Should I major in Japanese Studies or Japanese literature? Or should I do something else entirely? Do you know any exchange or scholarship programs that could help me? Do you have any general advice?

You should major in whatever interests you academically and as a career choice. You don't need to major in Japanese to teach English here, you can have a degree in sculpture and still get a job in an eikaiwa. Some say that's not much of a career but it does pay the bills and honestly most people who come here aren't going to get rich anyway so if that's not something that bothers you then go for it. As for translation/interpretation services, it's a tough job, you need to be really good at Japanese, better than someone who just studied it at undergraduate level.

That degree in sculpture will also get you on the JET program by the way (if you impress during the selection process), so in short you should study what you want, but don't expect that studying Japanese will make you that much more employable here because it really does depend on the field you go into. You want to be a journalist who covers Japan or Japanese culture? Japanese studies is honestly not a bad option. But for teaching English? Pretty much a waste of a college degree. You'd be better off studying applied linguistics and selling yourself as a great educator rather than a great Japanese speaker.

You don't need a bachelor degree to work in Japan. I myself only have a technical school degree in international business management and work in investment real estate with a 5 year international worker visa.

What you actually need is fluency in Japanese (I mean actual fluency, lightyears beyond the pathetic JPLT N1 which is barely business level) and the ability to convince your prospective employer that they have a valid reason of hiring you over a Japanese person.

Exchange programs are extremely competitive and hard to get into. I myself tried and failed to qualify almost a decade ago. I then took out a big bank loan and went for the study in Japan ➡ find work upon graduation route instead.