Thank you everubody for your great tips!
direngreywewe: I'm sure you'll go to Japan sometime ^^
In august I couldn't dream of going to Japan, but I spoke with my father and said. "If I start saving for a trip to Japan now, and I still want to after a year or more when I'll have enough money to pay most of it myself, Do you think that there would be a possibility that we can go to Japan then?" And after a while (about two months) when he saw that I was really serious we started to talk about it and he said that we would go to Japan sometime befor I was 18 (I'm 14). And now, a half year after I first talked to him we've decided that we're going in october ^^
Good Luck!