Dual Citizenship?

Hey I am just wondering what are Japans dual-citizenship policies? I was born in Chantancho, Okinawa in 1991, and ever since I was little I've always wanted to visit the country I was born in, with some more milder influences, culture, food, anime :P.

But when I was younger I remember asking my parents when I'm 18, am I able to live in Japan? I was told once I'm an adult my dual-citizenship is void. So I am wondering, is that true? Or has anything changed in the past 17 years?

Thanks in advance!

Is at least one of your parents Japanese citizen?
Unlike US, you aren't entitled to be Japanese citizen just because you were born there. (Except that your were born in Japan and your parents were unkown.)

If your parent is a Japanese citizen, you have to make a choice which citizenship when you become 22 years old as Japanese government does not allow dual citizenship.
If you want to have Japanese citizenship, you should contact city office where your koseki is filed.

http://www.moj.go.jp/ENGLISH/information/tnl-01.html

Articles 14-16 above says that you must choose one nationality by the age of 22 or risk losing your Japanese nationality.

In reality, I've never heard of anyone who has ever lost their Japanese nationality for failing to make a choice. There are many people, including myself, who has remained a dual-national after the age of 22.

Jon I saw on another post you wrote you were born on an American military base.

Is your mom or your dad Japanese? One of them has to be Japanese for you to claim Japanese nationality. If they are both American or non Japanese, then no you don't have or claim Japanese nationality.

Being Born in Japan by itself is not case for nationality (Japan uses different standards then the US or some other countries)

And strictly speaking, being born on an American base in Japan (or any other country), you are technically born in America regardless of which country the base is on (because Military bases, embassies etc are territories of the leasing nation and not the host nation). So for example if you were born in the US Embassy in Germany, technically you were born in the US and not Germany.