Being alone in a foreign country

Luckily, Japan is a pretty foreigner friendly place. In the big cities, there's usually enough English signage/advice that you can get by if you don't know any Japanese. If you're daring enough to explore in the quieter places of Japan (which you should definitely do, if you have the chance) you won't find as much English help (or people who know it) but most locals will be glad to try and help you however they can, even if the communication might be a bit tough.

Speaking from my experience in Japan, it is a little tough sometimes to be alone. A couple times in Tokyo, I got overwhelmed by all the people there, I needed to take a breather every now and then. But the great thing about being alone is that you can go at your own pace. You can do as much or as little as you want each day, which makes travel a little bit easier. You give up a little bit of companionship to have the freedom to do what you want to do, when you want to do it.

Plus, I remember many times that I got lost in Japan, but glad that I didn't have to worry about explaining the fact that I got on the wrong train to anyone else ^^;

You'll have fun. Just have a pretty good travel plan in place, which is just common sense. You know, what you'll do for food, where you're gonna stay, stuff that any good traveler would do. After that, you'll be fine.

Jam it back in, in the dark.