Have you made a will?
One thing I found out during the process is that foreign residents of Japan fall under the law of their country of nationality, NOT Japan.
This means that you cannot make a will here in Japan, and your estate will be handled according to the law of your home country, not Japanese law.
In the UK at least, dying intestate (without a will) makes everything much more difficult, and means it could take a long time to finish the process so that my wife and family receive my assets, especially as they are foreign nationals living in another country.
I don't expect to die anytime soon, but if I got hit by a bus tomorrow at least my family wouldn't have to go through a painful bureaucratic procedure on top of everything else.
I made a will online using this service provided by a law firm in the UK. It was cheap (36 GBP) and they were very helpful answering questions over email. I presume similar services are available in most countries.
I have also made a document listing banks and account numbers for my assets, to help my executors.
It might seem like a big hassle, but the whole process of researching options, writing the will, and listing assets only took a few hours. A good time investment for peace of mind.
Happy New Year! I hope 2015 is a happy and successful time for everyone :)