Nara Map Navi shows your current location on a sightseeing map of Nara, which also marks the city's many places of interest.

You do not need to use a Japanese cell phone carrier service; just make sure Airplane Mode is disabled (and GPS is on).

Download the app before you visit Nara, and all you have to do is launch it from the Deer icon once you get there.
The current location and default map is displayed. You can select different language versions of the Nara sightseeing map (Japanese, English, Korean, and Spanish).

You can also select a cycle route map from the list of available maps.