I am 14 years old and my dad has full custody of me. He is in the marine corp and stationed in okinawa,japan.my parents were never married and I have been telling him for over 2 years that I want to stay here in the united states with my mom but I don't know how to and my dad keeps telling me no but I really want to stay here with my mom and my younger siblings

Well since your father has custody he does have that right. It's his decision and no matter how much you don't want it, he can take you. The only other way he wouldn't is if your mother petitioned the court that it would be in your best interest to stay in the US. She would have to explain that it would be in your future's best interest to stay here.