For what purpose? What will you use maps for? Will you be driving or using public transportation.

For general walking tourism, I have always just cut out relevant pages from a good guide book and not wasted time with electronics. Most city's tourist information offices will give good maps for the asking.

If you will be in Tokyo, you will get more use out of a good subway map than a street map. For Kyoto, the large brochure they give out at the Tourist Information Center in Kyoto Station has the best tourist map I have seen. They will also give you the "Bus Navi" map which you can also download at: http://www.city.kyoto.jp/koho/eng/access/transport.html