Anyone who pays any kind of attention to the music charts in Japan knows that for many years now they've been a joke.
Year-end charts are increasingly clogged up with mass idol collectives, sales buoyed by multiple purchases from "otaku" (obsessive fans), encouraged by marketing gimmicks that tap into the most primal consumer instincts of the fanboy's reptilian brain.
One gimmick that has caused controversy recently is the use of music cards with a download code for a particular release, usually made available at a much lower price than CDs, and which permit multiple purchases of the same MP3.