HUGE fan of Japanese, but where can it take me in life?

No matter what you do, knowing Japanese will be an et. But why not talk to your guidance counsellors? They should be able to give you some ideas about what you could end up doing. Even your Japanese teacher(s) might be able to help, or at least give you more information about what the job market is like in Japan. If you're already considering specific colleges, you can research or contact their Foreign Language departments and see how good they are and whether or not you'll be able to continue learning the language there.