There's good information in the earlier responses. The Wikipedia article takes awhile to digest but is very informative. "Dori" is one of the Japanese words for a street, so your question refers to a street that happens to be one with a name, "Kaigan," in a specific "ku," which is a ward, or kind of a smaller section of a large city. Just entering the address you asked about in Google maps takes you straight to the Hyatt Regency Hotel in Yokohama. The three digit/four digit combination at the end is a postal code, similar to US zip codes. The 5-25-3 is not exactly a street address. It is a progressively more specific location in the subsections of a city, ending with a block number and a building number. In older parts of cities, the street numbers were assigned in chronological order, and vestiges of that system continue. That's one of the many reasons that you'll see a lot of maps - in subway stations, on the sides of buildings, at major intersections, etc. Gradually you'll find yourself closer and closer to your destination, and the process is not as difficult as my description makes it sound.