Why do I have a feeling that he, rather than feeding ghosts energy like our protagonist, is taking energy from them in some fashion? So poor Miss Tea Suicide might go poof because of him, with his next target being a certain dead boss.
welp, that ghost harem problem solved itself. Just let this lad take them and leave MC and Karen to ship.
... but yea he's Probbaly gonna be an exorcist and MC will have to pop in going "no you cant exorcise my harem!" (never mind karen already exorcised 2 of them).
New guy just wants to be like Dan Aykroyd in Ghostbusters and get some of that ghost sex. Before you know it, he will be stealing all of the waifu's from SquigglesJP.