Although it is not certain that the two crimes are related, they may be linked to the "botched computerization of Japan's pension records" in the mid-1980s:
Millions of those records have since gone missing, outraging the elderly and contributing to the resignations of two prime ministers. The mess continues, and many Japanese fear they might not receive full pension benefits when they retire.The murdered man and the man whose wife was attacked "are believed to have had influential roles in formulating the controversial pension policies."
Those of us who provide records management guidance to governments or who preserve and provide access to archival government records always emphasize the role of records in documenting and protecting citizens' rights to vote, own property, and receive benefits to which they are legally entitled. The scandal engulfing Japan's pension system exemplifies what can happen when governments aren't up to the task of creating or maintaining good recordkeeping systems: millions of records were lost in the transition from one system to another and were never properly recovered, and a Japanese government inquiry subsequently revealed that the nation's pension administrators have long been guilty of "sloppy" recordkeeping and other dubious practices.
Let's hope that the authorities quickly arrest the perpetrator(s) of these attacks -- and that Japan's pension administrators are able to clean up the appalling mess that they have created.