If anybody knows why the series was dropped in 1994, or if there are any plans to continue it, do post here.

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Not sure it if is helpful, but I can comment a few things about the publication of Dragon Pink.

The series was serialized in Comic Penguin Club. Chapter 22 can be seen in the Nov.1991 issue https://e-hentai.org/g/255582/58574c76af/.
That chapter is in the 3rd volume, released in July 1993 (Tatsumi Comics). Volume 4 was published in July 1994 (Fujimi Comics), just at the time of the anime adaptation, hence the extra anime drawings. There are large gaps between chapters and tankoubon publications, so it is hard to get any conclusions.

It happened that the publishing group was having some drastic changes in book publications at the time (the Tatsumi Comics line was dropped soon after the publication of volume 3), but this may not explain the unfinished ending, as Penguin Club continued publication (and is still alive by now).

Another theory is that the author being involved into the anime adaptation, he could not find time to finish the story. Or there is a conclusion, but it had too few chapters and nobody cared about publishing them...

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