Well, if the translation quality of the Lairs Of The Hidden Gods books is anything like the translation of this book, that would be part of the problem. Queen Of K'n-Yan takes a cue from a Lovecraft revision story, The Mound, and features the miraculously preserved body of an ages-old princess, found in China, and upon analysis, revealed to contain reptilian DNA. That's probably what the cover refers to.
It actually seems like a well put-together novel with some really creepy moments and horrific imagery, but the language is very drab and pedestrian. It may well be that Asamatsu Ken's natural style is drab and pedestrian, but I suspect the translation is to blame.
I don't have the 4-volume set. I was curious to read Ken's novel because The Mound is such an amazing story and I wanted to see what he would do with that influence, but I have a lot of other Mythos-related fiction I want to read before plunging further into the Japanese variant.