I have a japanese wife and child from my last girlfriend.
Did you have a child out of wedlock?
It was accidental, we didn't plan it or anything, we had fun and... well...
Regardless of why or how your kid was born, it happened. It's good that you accept it. You will feel good about yourself if you are an attentive, caring parent.
Yea, I know, I was wondering how to tell my kid eventually.
That can be tricky, but always remember she is your kid and your current wife is her mom. It would have to be a joint decision between parents. Love her and don't worry so much about the prerogative.