"Anything goes in Japan when it comes to sex as long one does not get caught"?
Pretty much everywhere in the world is like that! Even countries where LGBT are killed won't do anything as long no one knows about it.
Now, what I think the character might have attempted to say is that in Japan - as long they keep their sexual preferences in private - it wouldn't really matter.
What a weird character. Not to mention, she also seemly doesn't know the meaning of foreplay or anything like it. I feel bad for her girlfriend.