Parking in Japan
Parking in Japan is actually quite complicated. You don't need to be in Japan very long to notice that there is not much street parking. There are some parking metered areas, but there are way more cars in commercial car parks than there are on the streets.
In fact, it is basically illegal to park on the side the road in Japan, unless there are signs to say it is allowed. It is important to remember this, as no sign doesn't mean you are free to park on the side of the road as you wish.
If you are in the countryside or quite remote areas in suburbs of cities or towns, it might be more possible, but even then you need to be careful. In residential areas parking in front of someones house that is not related to you can cause conflicts. At all times you are best to use car parks if you can.
Firstly, it is best to know that in Japan you need to have a car park in order to own a car. That's correct. If you don't have your own car park, you cannot register a car in Japan. Part of the registration process is to have the police in your area verify your car park, and this verification document that the police issue is needed to complete the registration of your car.
So, next, you need to be careful when parking your car in Japan, as an unmarked car park does not necessarily mean it is free for you to use. Large car parks like those at department stores will generally give you a ticket as you go into the car park, and then you will pay using that ticket on the way out. If you shop at the department store, they will have a minimum level of purchases you need to make before the begin giving you discounts on your parking (the usually give you 1 hour or 2 hour parking vouchers).
Big shopping malls like Aeon may have free parking, as do supermarkets. However, in larger cities such as Tokyo and Yokohama they may charge you for such parking also. Some family restaurant chains and other restaurants will have their own parking too. Just be careful, some of them charge and others don't, but they generally don't allow you to park there is you are not using their restaurant. If you get caught using a restaurant car park and you don't have a receipt for haven eaten or drinking there, you can be fined quite significantly.
One of the most popular parking currently is what they call in Japan "Coin Parking" or "100 Yen Parking". Be careful, as 100 yen parking doesn't necessarily mean 100 yen per hour. Generally, actually it is 100 yen per 30 minutes, or 100 yen per 20 minutes or in some very urban places 100 yen per 10 minutes. However, these rates generally come down to be a double or triple cheaper at night. Many of the smaller coin parking areas are not fenced in or having a tickeinting service on the way in and out. Often they will have some kind of metal plate that will lift up in front of your car, or in the middle of it, after you have parked for 10 mins. This middle plate disables you from leaving the car park until such time as you have paid your parking fee to the machine that will be located somewhere within the parking lot. Your parking spot will be numbered in this case. You will need to go to the parking machine, put in the number of your car park, and then place into the machine what you owe for the time you have been there. On paying the money, the metal plate or bar will automoatically come down, and as long as you leave within 10 minutes, you will be OK to drive away. You can see an explanation of how to use these "coin parking" or "100 yen parking" here; http://www.youtube.com/watch?v=ymDj3U0a4Cw&feature=share&list=UUICcsm5ulE354i0cCN5SWVA.