Getting a DL in Japan is expensive but depends on where you are from.

I would recommend getting your license in Singapore first, then get an International Driver's Permit (IDP) which will allow you to drive in Japan for one year. If you will be staying longer then you could convert your Singapore License to a Japanese one. Know that the conversion process requires a written and practical test, and costs at least around 10,000 yen and will take as many as several months to complete.

But please take note of this, it was mentioned above by someone, but may not have been highlighted enough: You need to have been IN SINGAPORE for at least 3 months after you get your Sin licence. You cannot be on holiday in another country! You must have at least 3 months duration before the Japanese will acknowledge your Sin licence. That is why they often ask for all your old passports - they will determine if you have been at home for 3 months or not. Seems silly, but it's the way it is. ;)

It expires on your third birthday after receiving the license (2-3 years depending on the exact timing of things). Then you must renew which requires a short refresher class at a police station.

Where are you planning on living? Are you sure that you will even need a car? If you are in a big city it may be more of a hassle than a benefit to own and store. Public transportation in Japan's cities is some of the best in the world.

In fact, I think the practical test for "gaimen kirikae" is shorter and easier than even the practical test to get a Japanese learners permit.