I recalled my miserable driving tests in Kumamoto when I read the article below. I failed three times and only passed the test on my fourth attempt. I know some people who renewed the international license every year at the original home country and used it to drive in Japan. However, it's not really legal. I once heard from a former colleague who studied in Japan for his degree, he was almost deported back for driving with a international license after two years in Japan. Since he was a student, the judge gave him a lenience sentence which was only fines. So, he borrowed money and paid off the fines, he said he had bread only for almost a year to pay off the debts. So, better get the license the proper way.
First, I worked in Kumamoto City for a year and I took train to work. The second year, I had to transfer to Nakatsu in Oita 中津市、大分 which was not very convenient in terms of public transport. So, I had to take a driving test to drive in Japan. International driving licence is valid for the first year only. Since I had my original driving licence from Malaysia (pass on my second attempt because I forgot my seat belt the first time around), I could convert the license to a Japanese driving license, it is called 外国免許切替. However, for direct conversion, only a few countries are qualified, info here.
For others, like a Malaysian driving license holder, I had to take a written test and driving test to convert my license to a Japanese license. It's a big discount compared to what the Japanese people had to do to get a fresh new driving license. To many Japanese, the written test was what they dreaded the most. It's a very difficult multiple questions test and many failed at first attempt. So, in Japan, there's tuition class for driving license written test. However, for this license conversion written test for foreign driving license holder, it's just a common sense 10 multiple choices questions. I personally found it easy.