[mercedesjin]

I think the first step is to tell your girlfriend.

I think you two need to talk about it so that you can figure out the right answer for yourself. If, based on your conversation with her, you decide that you'd rather be with her because you think that you'll have a long future with her - then, that would be the best choice. Stay home. Japan will always be there. You'll have many opportunities to go there later in life. If you really love your girlfriend, and you think that you might love her for a while, then I wouldn't give that up so easily.

But if you speak with her and it turns out that you two aren't sure that you'll definitely have a future with each other, then maybe it's best to follow your dream. You'll have many opportunities to go to Japan later in life, but if your reason for staying isn't that important, then hell - you might as well do it now.

Ultimately, though, that's something that you should choose for yourself.