minimini or Apamanshop.
Even if you don't go through these agents, they will give a good idea of what properties are available in a given area, and how much those properties cost.
And, aside from location and apartment layout, there are many other details to consider in your apartment choice. Let's look at some of the common criteria Japanese people look at, starting from the outside environment:
Sometimes the key to cheap rent is a building's age. Apartments in 30 year old buildings can have half the rent of apartments in newly constructed complexes. The tradeoff is, of course, style and comfort--and less obviously, safety. An older apartment won't look so good, and it might have pest problems. Additionally, older buildings are more prone to earthquake damage. Japan experiences enough large earthquakes every year for this to be pertinent. A rule of thumb a Japanese friend once taught me is to look for buildings constructed after 1990, around the time stricter building codes were enacted in Tokyo and elsewhere.
Distance from a Station:
Japan's public transportation system is one of the best in the world. Unless you are living in the countryside, you'll want to seriously consider commuting to work by bus or train. Apartments close to stations cost more.
It's worth checking details of the bus or train line served by the apartment as well: some lines do not have rapid service or (like Seibu Shinjuku or Chuo in Western Tokyo) are notorious for packed, uncomfortable rides during commuting hours.
Along with prime location often comes increased noise. If the apartment is on a busy street, midnight traffic might keep you awake. If the apartment is near a nightlife district, noisy drunks might keep you awake. If possible, visit the property's neighborhood once at night and check its noise level.
In a multi-storied complex, apartments at the ground level will be slightly cheaper than apartments on higher floors. This is a perceived safety issue, and especially Japanese women believe that living on the ground floor carries risk of robbery or assault (or perhaps panty-theft when hanging laundry out to dry).
Apartments with a balcony facing the south are considered best. These apartments will get the best sunshine throughout the day. Next best are apartments facing east, since these get the rising sun in the morning. The "worst" apartments by Japanese standards are ones that face west; these apartments aren't as well lit in the morning and glare from the setting sun is unpopular in Japan.
If you have a car, parking availability is another key point to consider. Unless living in a small town or village, car owners are required by Japanese traffic law to own and register a parking space. Some apartments have adjacent spaces and others do not. You will almost certainly be required to form a contract and make a monthly payment for the parking space, even if it is on the same property as your apartment. In small cities, a parking space may be as cheap as $20 per month. In prime neighborhoods of Tokyo and Osaka, rent on a parking space can exceed that of a small apartment. I have heard numbers from $100 per month up through $1000 per month.
Of course, it is also possible to find a parking space separate from your apartment! However, the parking law requires the car to be within some 2 kilometers of your living space. (Check your local police station for your city's specific distance designation.) The Japanese site Parking-point can help you find spots and prices in your area.
Apartment Criteria (Inside)