Actually, the hardest part of navigating Tokyo is going to be when I exit a metro station, and there is no point of reference to know where I am because the streets have no name.
Usually, when I'm in a strange city and exit a metro station, I am very disoriented. So, the first thing I do is look at the street sign and find it on my map. After I identify the street on the map, the rest is easy.
Without the ability to do this, I will be basically castrated. I will be like a clueless wanderer in the desert. 'Landmarks', 'subway stations', etc are no substitute for proper street signage. I understand that this goes back centuries, to confuse enemies, but in 2015, you would think the Japanese would have remedied this by now.