I won't pull any punches; Datenshi-tachi no Kyouen, AKA "Feast of the Fallen Angels", is legitimately the worst anime I've ever seen.
A friend put this OVA on one night because we thought it was going to be hilarious 80s cheese, and the art style certainly looks the part, but it's not worth it. Every second of it is full of gloom and despair. Not in a good Oyasumi Punpun way, but in a way that makes you deeply uncomfortable and filthy...even moreso when you consider this is supposed to be an ero-anime. You'll find yourself watching Datenshi-tachi's enema scene, wincing at how hard the voice
actors scream over the horrible discordant synth background music, and remember, "Oh right, this is supposed to be sexy."
This was released by Orange Video House. You might remember OVH as the distributor of the Guinea Pig films...yes, *those* Guinea Pig films. One of the most famous shots from Datenshi-tachi is of Megumi - the blonde child on the VHS cover - having her eyes held open by the fingers of the Ugly Bastard (also seen on the VHS cover) while something explicit happens in front of her. OVH was proud enough of this shot to feature it on the sides of the VHS packaging and in promotional material.
The best way I can describe Datenshi-tachi is that it feels like a creepypasta. It feels like something I'd find on a beat-up DVD-R at the side of the road. I can't stop you from watching this if you really want to, but just be advised that it's a deeply uncomfortable ride and you're likely to hate it.