PSoH was a psychological horror series with a relationship between Leon & D that went from annoyance to kinda friends to "best friends raising a kid together" (Leon's little bro) to arguably Leon falling for D (I mean he quit his job & abandoned his family just so he could return a drawing? Sure sure. & he didn't seem to want to kill him like the way Howell hunted down his father).
Well, this is one of many MANY mangas I've read that suffered from Genre Shift. The horror & gore were pretty much completely stripped from the stories of people who visited the petshop. The 2ed grievance was that D & Fei-Wu lack the dynamic relationship of D & Leon, indeed they never really get along as time goes on. Lastly, when Leon finally DOES show up, D is already on a plane to another country. Fujoshis will also be irritated to learn that this series had no BL subtext whatsoever. (argh, it's just like what happened to With Love from Eroica).
The series SORT OF continues, in the form of a prologue centered around Soufu D (grampa). Chinese scans for the series have sort of stopped, but the series is apparently still going. Maybe only after it ends will we get back to D. One of the biggest gateways is that she's working on so many series at once that there can be a year between volume releases.
At least the art is still good. ::sigh::
Personally, I would skip this series outright unless another true sequel comes out of it. I would however recommend the Passage Han prequel, even if you can only find it in Chinese.