You would need a sponsor to help you apply for a visa, since you will not be considered an adult in Japan until you are 20. This sponsor can be a spouse, a school, an employer, or anyone with a firm legal relationship to you (a relative, director of Institute X etc.).
Short of getting married, your safest path to a visa is a having an employer sponsor you. This means putting yourself on the job market. Unless you have some amazing skill no one else can do and have a great handle on Japanese language, you can only help yourself by going to college. The application of a work visa really wants you to have a four year degree from a college or university (in short, a BA in the US). Plus while you are in school you can go on an exchange program or two, hardly have to study, and not be allowed to work! Only one thing left to do... ;-)
It seems you can work on a student visa, but there is paperwork to fill out and you might be turned down by the immigration office. Don't count on a student visa to earn you any money.
If you are an amazing muscial or drama talent with an established career and a producer in Japan wants to sponsor you for a entertainers visa, that would work.
Or you could be a pro sports star. That would work too.
You could always strip for money, but again, you would have to be 20 to be legal (I'm not being curt with you, you wanted all options, and this is one).
That is about all I can come up with now. Hope others can offer advice...