Question about getting married in Japan?

Question:

Hello,i'm 19 and so is my boyfriend. We're out of High school,and soon be going to college. We both want to go to college on base,but since he's half Japanese and i'm full American he is allowed to stay in Japan and I can't without a Visa,(Which for some reason the base college won't give me)And so we want to be together. And a way with this all working out is if we got married and i'd have the same benefits as he does. Could we do this at the age of 19? (By time i'm 20 I probably won't be in Japan anymore.)And I know you can get legally married in Japan when you're 20 WITHOUT a parents approval,but since we're both basically American can we weaver through that law?
Please don't make comments on how stupid this is,because I know what i'm doing and I know what I want.
Thanks in advance!

Answer:

Well, you can live in Japan under spouse visa if you are married to a Japanese.

Not the "same benefit". You can't get right to vote, etc.

You can get married without parents approval at 20, but not at 19.

>but since we're both basically American can we weaver through that law?

Not sure. But he's trying to live in Japan as a Japanese. So he's not "basically American"　Does he have Japanese citizenship? You only said that he's half Japanese.