Advice? Traveling to Japan

So my boyfriend is in the Navy, stationed in Japan. I’m living stateside. I just moved out into the house that we will both be living in once he gets out a year from now. He’s been there for a year already and I’ve only got to see him once since he left which was the beginning of this year.

He was going to come back and visit in January but he found out he can tack his leave on at the end of his deployment and get out faster.

So I now have the opportunity to go to Japan and stay with him for two months and get to see some of Japan. We had tried to plan this trip previously but my parents were so against it that we called it off.

Now that I’ve turned 20 and am living by myself we’re trying to plan it again. But my parents are getting in the way. My mother doesn’t think it’s safe and doesn’t trust me to be able to do it because I have never flown abroad. Even though it will be a straight flight and I’ll have his cousin here to help me throughout the airport. (he works there)

My parents would be okay with it if he was here to fly with me, but he isn’t. We have thought out and planned out every detail all the way down to travelers insurance and back up plans. But whenever I bring it up to her she finds insane reasons for me not to go. One being “what if you get arrested?” or “what if you’re in a coma and need surgery? You aren’t married yet so he won’t have any power to say go ahead.” the list goes on and on and just gets wilder. She has always said she wanted me to see the world but when I get the chance she does this?

So I guess what I’m asking is, should I do it even if my parents act as though I’m killing them by doing this? I know it would be good for the two of us and this opportunity won’t arise again.