OK so, I have been following this manga for many years. The art for the current cover is different because she/he drew that few years after the series begun (basically her/his art improved) and one or two years later, she/he remake the first chapter so that's why it looks really different from ch.1 to ch. 2. I think some people read Kingdom of Ruin, but they're literally the sequel of this series and there was so many references that I actually screamed. The author wasn't able to finish this series (because the company she/he was in was just terrible and did not have any human rights) but as far as I read, they have a really cool world building, and I really recommend this manga. Hopefully someone will pick up again because the plots get deeper as it go through the series.