I really liked this. I could understand that some people may be confused as the show does make some changes from the anime while also doing a poor job of explaining its premise. To sum up, this OVA follows 4 demons sent from Hell to the human realm to round up other demons that have escaped and are committing lots of murder. In order to try and blend in, they form a detective agency to investigate gruesome murder cases caused by the escape demons. With that out of the way, let's get into whay made this show enjoyable for me.
The show tackles a lot of dark themes. For starters, it's very violent. No one gets a simple, clean death. There's a lot of blood, very gruesome injuries, and very creepy faces when someone is possessed or deranged. Which makes sense. Demons aren't going to be gentle about how they kill people, they're demons after all. They relish in evil and chaos and so everything they do will seek to achieve maximum damage. Even when exorcising a demon, it's not a clean process. Rather it's a very violent for the host's body, and while they still live, it leaves a permanent scar on them.
Another thing I liked was how someone becomes possessed. Rather than the cliche "pack with devil" or black magic and being an evil person, instead in this show someone becomes possessed when they are most emotionally vulnerable. They experience either great trauma or emotional turmoil, making it easy for the demon to prey on said person's inner demons (for lack of better term). This was a great twist as it meant anyone could fall victim to possession, even someone who is genuinely innocent or good, as the demons feed off one's internal darkness instead of concrete wickedness. Piggybacking off this, this show tackles some mature themes such as sexual frustration, abuse, suicide, guilt, and other negative themes many shows typically shy away from or just hint at.
There are also some genuinely creepy scenes. The possessed doll in episode 2 is very eerie thanks to animating it in an alternate art style making it literally stand out in every scene. Some of the faces people make when it's revealed they are possessed are pretty scary. And there's a painting in the final episode that keeps changing as the plot progresses which is also well done and quite haunting.
However this show is not without its faults. One of biggest complaints is its reliance on cgi. Obviously this show was made at a time when cgi was pretty bad, and low budget animation cgi in particular, but unfortunately it really contrasts from the animation used in the rest of the show that it kind of pulls you out of it. The CGI works for making the doll in Episode 2 creepy, but when applied to entire scenes like the haunted house in Episodes 2 and 3, it just looks cheap and makes me wish they had just stuck to drawing the house scenes instead. A similar problem is since this is an OVA, the transfer isn't the best quality so the show sometimes looks grainy or like it has a filter applied to it. For the record I enjoy the art style and dark pallet as it works for the show, it would've been nice if there was just a crisper transfer or possibly a restoration done when porting to streaming.
The only other main complaint is that out cast of demon hunters really don't get much screen time and so as consequence, get very minimal character development. Most of the show actually revolves humans, be they possessed or side characters, with our titular character Enma taking a back seat in his own show the more it progresses. By the final episode, he's only in it for less than 5 minutes of screen time despite it being a 45 minute episode, and the resolution that happens is very rapid. It's not bad so much as you are left going "oh okay then I guess it's over". I personally would've enjoyed more development between Enma and his partner Yukihime, as they are mirror opposites of one another (male fire demon vs female ice demon) and early on it seems that a relationship may be forming between the two, only for that to never come up again until the very end of the show.
