Hell is Dark with No Flowers Vol. 1 by Yoru Michio

Seiji Tohno is a down and out NEET, living out of Net Cafes he's on his last few coins when one evening at Twilight, he finds himself lost. After wandering for a bit, he finds himself in front of a European style mansion and is quickly invited inside for tea. Once inside, he meets Shiroshi Saijou, who offers Seiji a part-time job, including room and board. All he has to do is help Shiroshi with his business. The problem is Seiji is 100% sure that he can't say no and that Shiroshi's business is no normal business. It may even be Hell on Earth. 

I can not begin to tell everyone how much this is exactly the story I've been looking for for months! This blends Yokai folklore and mythology with a detective style story reminiscent of Yokomizo. So much so that the second "case" in the book appears to be dedicated to him. And I can say with 90% certainty that I think Yokomizo would love these stories. 

So far we have delved into two stories that center around broken families, those lying to each other and betraying each other (very reminiscent of Yokomizo's works), people who have sinned and believe that have gotten away with it. The twist here is that Seiji can see these sins in the form of a corresponding Yokai, instead of the person he sees the Yokai that represents the sin, which is great because Shiroshi can send them to Hell (after giving them the opportunity to repent of course). This is such a brilliant use of Yokai, having them manifest in an individual, I busted out my own copy of Seiken Toriyama's Yokai Encyclopedia (a modern translation) to see if I could figure out which villain was which Yokai first! 

I genuinely can not recommend this enough, especially if you enjoy Yokomizo's Detective Kindaichi series. Thank every god ever. I picked up Vols 1 and 2 at the same time!