Smartphone rental is a good way to go for real time maps. If you must have a paper map, this one has block numbers and old major attractions should still be correct on there. http://www.amazon.com/Tokyo-City-Atl.../dp/1568364458

Having said that, even with a smartphone with data connection, and visiting every few years, I consider getting lost only once to count as a victory. Usually heading down an incorrect subway exit or perhaps on the wrong train. It isn't a usually problem as you can generally get off the train, go to the other platform, and backtrack for free.

Just take your time and print out the hotel map in Japanese and English so you can always make it "home" if the batteries die. If you are trying to visit a particular restaurant, check the route via Google Street View and also be sure to look up. Restaurants aren't always on the ground floor.

Should you get utterly lost, "Koban" is a police box and in most neighborhoods. They can help with directions.