That's when it's best! When I first started getting lost on my own, it was when I didn't speak a lick of Japanese. I'd just wander and wander. If I wasn't allowed to be somewhere, someone would give me the 'batsu' sign and I'd just move on. Besides, Tokyo is safe =D and your phone will have GPS.

My best friend and I sit in Cafe's and do that at the stations but when I'm with the guys, they're like "Stop that," or "Hey, you're here with me, remember?"