[GhostBlade]

Did you disappear or something? Anyway, it may even be best to go alone to Japan without anyone. Even if you go with your best friend there will still be many disagreements and one of you may be irritated at the other person most likely. If you must go with someone then make it only one person because you can always split up and do your own thing around the city in case of an argument or disagreement on where and what to do. When you go alone it gives you an opportunity to take everything in around you and you will be more aware of your surroundings because you know that there's no one you know near you so that can make the situation more exciting.

I know you may want to experience Japan with someone else by your side that shares your excitement but you can always meet other travellers at the hostels and this will give you a better chance to meet and talk with them if you're alone than if you were with someone else. When you're with someone else you may not care to meet other people because you figure that you have your friend with you so there's no need to meet new people and you just focus on your friend the entire time instead of people all around you. Being alone almost forces you to want to meet other people. I think meeting a bunch of new people at a foreign land will be much more exhilarating than going with someone that you've known for a long time and it may be a wise idea if you want to save the friendship that you care about because arguments on the road can be common.