Keep Circulating the Tapes - There is no official English translation, and until recently (2008) there wasn't even a fan one.*
No, the terrible translations of the first few volumes done by Obsession don't count.
The first five-and-a-half volumes have been scanlated thanks to the combined efforts of first Livejournal user Persepolis130 and later Scarlet Carnival; other than that, there are only text translations of a few later volumes. Even the Japanese print volumes can be elusive and expensive, although one can download raws both legally and not. For avid manga readers, it's series like this that have started them down the path to learning how to read and understand Japanese (and we're talking very flowery language and stylistic character usage from the 1970s here, so you really have to be fluent in and have a good grasp of Japanese literature already).
No Export for You - And sadly, given some of the subject matter, it'll be something of a miracle if this series does ever see an official English-language release.
