I see no reason for this story's existence.
I came here thinking this was an alien story, although horror is fine too. I've read few horror manga's before this but have read enough Lovecraft to have an idea of what I want in my horror. Specifically, entities whose motives cannot be understood by humans. Horror should show how little humans actually are in this universe, only these stories can truly bring an existential dread that really makes good horror.
In that vein, this manga was a toddler throwing a tantrum, thinking that gore and murder would make it horror. This is laughable and pitiable. All the characters, barring the father, ultimately had human emotions of hate, vengance, and what not. Mari's younger brother struck me as a misled and demented child rather than any horror being. The cottage arc was a major letdown when the murderer turned out to be a mere lunatic.The murder and gore scenes struck me as humans fighting other humans in petty swuabbles. The peak of this was the climax, which I did appreciate as true to the wishes of Lovecraft. Only for the romance to mute the ending's power, without any real date scene or kiss scene I expect from romance. Sad too, as the endings emphasis on poor romance muted the Lovecrafitan elements of the story.. The one positive was the father, whose conflicting values between duty and family gave me a deep empathy for him despite his murderous activities. Too bad he's not enough to save this manga. This was a waste of my time that would have been much better spent reading Lovecraft himself.
3/10.