There are two types of things that can be inherited when a relative dies: assets and debts. Most people will be happy to accept the assets of a deceased relative, but few will be willing to take on their debts. In addition, in many cases it would be unfair to force an heir to pay off the debts of a deceased relative.
Japanese laws regarding probate and inheritance generally only apply to Japanese citizens. This means that foreign nationals who lived, owned property and die in Japan will still have their assets distributed under the law of their home country, rather than Japan. This also includes foreign nationals who become permanent residents of Japan.
An International Driving Permit will allow a driver licensed in another country to drive legally in Japan. However, the permit is only good for one year, at which point any foreign resident who wishes to drive in Japan should apply for and take the Japanese driving test.