Well, the film/OVA is quite old, so it is no wonder, that the animations are "very simple". Thinking back to stuff like Ghost in the Shell (the very first movie!) and other animes from that time, its probably okay this way.
But honestly the greatest part of the story stands in the description which is proof of the boredom you get while watching. Eiji and his fiance playing lovey dovey while you just see a bit kissing and suddenly a demon is ripping her arm of. She survives with the goal to encounter that demon again and kill him? why is obvious to the audience in no time and I dont want to right any spoilers. So... believe me, that the story isnt just plain here, the few bits of "18+/Adult stuff" are either just a short scene of hardcore-kink-pictures being repeated for no reason or at the end... well... that was quite a joke I cant laught about... =_= that XXL-Demon at the end has a goddamn second mouth(???) in his chest which looks just like a stupid version of an vagina with teeth and other... uh.. stuff... whatever. It was lame. that stupid fiance could at least have been pregnant by "accident" with the demon since the subs where kind of missunderstandable. However... the entire movie was senseless till the point of absolute boredom. I watched it just to give it a try and becauce I thought one of my favourite Seiyuu would have a role there. But either was the info totally wrong or he wasnt as skilled back in the days, as to give his voice that distinguishing tone, I can just recognize in his latest works.
I really cannot recomment this, since I dont want anybody to fall into despair over so much boredom. (show less)