its like this: for americans the birthplace is important point to determine citizenship. but for germans its the bloodline, so this means what citizenship your parents are.. so it doesn't matter where i was born, i am german because both my parents are german. thats why i have a german birth certificate, even though i was born in japan.
this is a very complicated situation, still donjt know if i should pick japan or germany..?
I just mentioned my case. I know that Germany Citizenship is determined by bloodline and not the land of birth. It doesn't matter what Citizenship you were born in to. What matter is the "place" where you were born.
That's why you need to look at your birth certificate and see if it says that you are born in Japan or Germany.