Well, of course the next When They Cry is going to be a murder mystery. (at least I would think so)
Most of the When They Cry series take place in a rural place (Higurashi- small town; Umineko- island; Ookami- small town; Higanbana- abandoned school), murders occur, and an animal that "cries" is somehow related to the story. (Higurashi- a cicada is always heard; Umineko- seagulls are heard after the typhoon; Ookami- legend of the wolves)
And honestly, if I had to rank Ryukishi's When They Cry works, it would be Higurashi no Naku Koro Ni, Umineko no Naku Koro Ni, Ookami Kakushi, and Higanbana no Saku Yoru Ni.