Free downloadable walking maps and guides for Japan
iPhone - iPad apps
There are maps you can download on your iPhone or iPad for several cities in Japan.
To find them do a search in the app store for "gpsmycity japan" (quotes are not necessary).
The screen shots attached here show you what the apps look like.
There are free versions and paid versions (.99).
These apps provide you with self guided walking tours with detailed tour route maps and navigation features (navigation features in the paid versions only).
All the data is built into the app so you don't need Internet access to use it once you've downloaded the apps. However, to get the detailed navigation you may need to be connected - and unless you have some sort of data plan for low cost roaming - watch out! Remember, normal roaming and downloading data in Japan can cost you a bundle! There are data SIM cards available at Lawson and other convenience stores, but I haven't used one of those so not sure if you need an unlocked phone to use them.
I haven't tested these yet as I just discovered them today. Why not download one of the free ones and if you like it maybe it's worth upgrading to the paid app. That's up to you.