This is to the best of my scant knowledge. The government is sick of taking responsibility for people injuring themselves with old electronic devices. A short while back they initiated something similar to UL here, which manufacturers had to comply with. That wasn't good enough so they are making this new law which outlaws stores from selling anything made before 2001 that plugs into the wall. Sucks for the japanese because they have a lot of electronic devices, like smalll vacuums, rice cookers, wash machines, fans... and of course cool old synths and mixers and drum machines and what not. Alot of people think that they are doing this just to boost the sales of brand new products. Japan has the coolest and the most vintage used gear stores I have ever seen anywhere in my entire life.
here's an english link to read:
http://www.cp.org/premium/Online/Mem.../z030401A.html