Traveling alone is a unique experience and I'm glad I did it. I would heartily recommend Japan to those traveling on their own (especially women). It's a safe and clean place. I didn't feel vulnerable. I didn't catch anyone leering at me. I wasn't groped. People went on their merry way and didn't pay much attention to the tourists.
Not as many people spoke English as I'd expected. As a result, I made an extra effort not to get lost because I would have a really hard time asking for and understanding directions. Some folks looked frightened when I approached them. I think they would've run away if they could. I've heard that many Japanese have never really interacted with foreigners.
Hotels weren't as expensive as I'd expected, but other things, like clothes, were crazy expensive. Jeans at the Gap went for over $100. Even average clothing stores were expensive. Food, however, was good and cheap. I ate mostly soba and sandwiches during the day and bought my dinners in the department stores in the evening (the basement floors are a mecca for wonderfully prepared dinners and desserts). The two times that I had sit-down meals in restaurants, I had difficulty getting the check. I'd forgotten my conversational Japanese book and didn't know the word for check, so I opted for what works in the U.S.-- I flagged down the waiter and pretended to write my signature in the air. It's the international sign for 'check, please,' right? Ummm, no. Both times I did that, the waiter brought me a pen. Yes, a pen. I eventually realized that since Japan is still a cash-based society, waving your hand in the air doesn't necessarily mean that you want to sign for a credit card.