Wow. It's truly absurd the laws that get passed in the name of public safety. (It's OK to own the non-compliant stuff but not OK to sell it? Uh, OK.) Has there been an epidemic of electrocutions in Japan from using old guitars? Doubtful.
On the upside, it sounds like a good time to fly to Japan and buy a bunch of vintage synths and stuff:
With just three weeks until “judgment day” second-hand instrument shops, retro video games shops, antique lighting stores and antique gadget emporia are slashing prices by absurd margins, fearing that their stock will become worthless overnight. And because it will not be illegal to own a non-PSE product, customers are indulging in a buying frenzy.