For all the comforting reassurances in this thread, I think it's incumbent on me to mention one famous case of a family of foreigners who got lost in a godforsaken corner of Katsushika Ward. Nobody really knows what became of them, but there is some speculation that they got trapped in a labyrinth with no street names and were eaten by the minotaur. It's also possible that they fell into one of the snake filled pits that were installed by the Shogun to stymie invading armies. It's a wonder that nobody has dismantled those. I recommend carrying some wax as you travel around Tokyo. If you find yourself really stuck somewhere you can grab some feathers from the crows that are picking at the trash in the streets, and fashion yourself a pair of wings to soar above the city and escape.