how will i survive in japan?

i can not afford an international school but i can't speak japanese that much.what should i do?
First i would suggest attending a language school and learn japanese. Believe me, you can't get by with English in Japan. People 'maybe' understand fragments of the English language, but they often will respond back to you in Japanese. In general people in Tokyo are a little better in English, but anywhere else, you can only communicate in Japanese. Once you have mastered Japanese, then you can attend the regular schools with affordable tuitions.

what do i have to do to get into the school?
assuming that your passport is still valid, japan offers mandatory education through high school. so all you have to do is apply for the public schools in your district and you will get in. if you plan to attend private schools that'll be another story.

when will i graduate high school?
this depends on how long you stay at the language centers. it you are learning jap from scratch i think you will need at least 2 years to master japanese, so you will graduate high schoo when you are 20 (instead of 18)

can i work there?
the answer is yes assuming that your passport is valid.

>Will i still be able to live in japan until I graduate high school?

The short answer is NO.

All classes in Japanese schools are in Japanese. So you can't follow it without Japanese skill and you would not be admitted.

Without school enrollment, you can't get student visa and can't move to Japan.

All you can do is to apply for an exchange student program.

>I want to stay in japan a my friend's house with her family for a few years

Did her parents allow you to stay there? Normal parents do not allow another kid under 20 to stay their house for a few years.

Addition:
OK. I did not read that you have Japanese passport. So you can live in Japan without visa.

If you are Japanese citizen, you would be treated as returnee (帰国子女) in Japan. This returnee means Japanese kids who used to live in other countrires.

There are some schools who accept returnees. You should find those schools. But who pays tuition?

dude,ur screwed. haha
just kidding. ur english is weird. but better than 99%of your futur class mates. u shoud brag about it.play confident,laugh at ur mistakes in japanese, and use ur gaijin card as much as u can.
if u want to survive, do not try to blend in.u have to stand out.
seriously.
good luck.

International school won't accept any entry without gurdian's permission and financial support in anywhere.

Japan is not a state of USA. It is independent country. You must need visa to move into Japan to stay more than 90days.

Your childish way of thinking such can't be accepted any place in this real world.　To change yourself, you should do your duty all what you have to do at first comletely. It seems you just want to run away from reality. Life and the world are not so easy as you think.

...... OK, you are Japanese citizen, now I got you.....

Then, anyway without parents permission underage child can do nothing. It is parental responsibility. Without your parents approval, you would have very few chance to survive in Japan.

You need financial supporter anyway.

Your best bet is to complete your highschool in the States and then apply for a university in Japan.

Reason 1: Highschool in Japan is extremely competitive and it's completely different from the education system in USA. You will not be able to get used to all the pressure and the new system.

Reason 2: Highschool in Japan is taught in Japanese, unless you go to the international schools.

Reason 3: You will be asked to have a guardian, and in your case, your friend's family will be your guardian. You're underage, and you won't be able to stay, signup for school, etc. in Japan without a guardian.

Reason 4: After you've graduated highschool in USA and obtained a student visa to go to post-secondary in Japan, you're allowed to work a limited hours a week as per your student visa. However, the job market in Japan is quite competitive and you will need to know Japanese (at least be able to converse in Japanese).

Reason 5: Because both your parents are Japanese, you might be qualify for the local student rates for university. I know that international students have to pay a lot more (just like other countries).