In the 1970s, cheap sonosheets (phonograph records printed on thin, flexible sheets of vinyl) became quite the rage in Japan. Like all fads, these recordings have largely disappeared - but you can still gawk at the fantastic cover art over at Pink Tentacle:
Widely available from a variety of publishers, the most popular sonosheets featured theme music from TV anime, manga and tokusatsu, and they often came packaged inside booklets featuring colorful artwork. The sonosheet boom was short-lived, though — many companies went under as the market became flooded in the 1970s, and the phenomenon all but disappeared by the 1980s. Here is a small sample of the vast array of sonosheet cover art from that era.