I got reinacarnated in another world but no one knows that grabby aliens are conqering the galaxy

Okay, I got one. A single-volume horror story:

MC is an overworked office worker and moves into a "free" house in the country to get away from the stress of Tokyo city life. Winding down and adapting to the slow life in the countryside isn't easy and unusual sounds and movements outside the room scare him at night. He befriends the locals, helps out an elderly couple tending to their vegetable garden, and gives a young kid who gets bullied at school some helpful words. But the country sounds at night still keep him from any relaxing sleep and the ghostly silhouettes he sees in looking at his house are getting more.

The people start to act strange around him and the elderly couple tells him that they are afraid for him and they make some vague comments about the woman who lived in this house before him. He can't get that comment out of his mind, so he searches for what happened to the previous tenant. After some internet searching he gets in contact with a guy from a small occult magazine in the next larger town over. He tells him that that house is haunted and that the previous tenant saw ghosts as well and was found dead in her old school tatami bedroom. The official report said that the woman killed herself by inflicting several deep scratch wounds all over her body after a psychotic breakdown, but the occult guy says that it was the vengeful ghost of the original owners that built the house and lived their entire life in it before getting murdered in a random break in. He says that they and the previous tenant now haunt the house and gives MC copies of his occult magazine where he wrote articles about the house. MC reads them on his bus ride home and decides to grab his things and leave right away. But even for a seasoned overwork-veteran, the consecutive days of running on adrenalin without sleep catch up to him and he faints in his bedroom while packing his few belongings into a moving box.

He wakes from the sound of someone or something trying to get into his bedroom door which is blocked because he collapsed against it with his backpack. The first thing that he sees is the door being slowly pushed open now that he got up and isn't leaning against it anymore. Then he realizes that all the color has gone from the world and that there is a constant eerie ringing sound that only gets overpowered by the screaming sounds of the thing that tries to get into the room.

When the door finally opens he sees grotesque withered yokai monsters shuffling towards him. He grabs a rice cooker from the moving box and bashes the monster's head in. The other monster gets visibly agitated but he manages to kill it as well. He doesn't give a shit anymore about his belongings and just takes the meanest-looking kitchen knife he has and tries to flee the house. but outside is colorless as well and the ringing sound gets louder and more annoying in pitch. There are also more monsters in different variations. From slow ones who try to attack him from a distance to big and strong ones who rush into close quarters.

After much struggle and several fights against the yokai he manages to flee the village and makes it into the town where he gets in contact with the occult magazine guy and he is visibly disturbed by the story he hears. Together they go to the police and there he is arrested. The police find the residents of the small village all stabbed to death and MC gets locked away after being found guilty of mass murder. He is now waiting in a monochrome horror cell waiting for the day the monsters come for him to kill him. Still hearing that ringing sound until the day of his execution.

The twist is that at some point the reader realizes that something isn't right and hopefully only at the end it becomes clear that the monsters were just in his imagination and he killed all the people he befriended. The second twist is that at the very end, it's unclear if the haunted house made him have the psychotic breakdown or if it's just a coincidence that both he and the former tenant had the same hallucinations. Maybe the last scene could be the house with now 4 ghostly figures behind the window looking towards a moving truck with a new tenant moving in.

I decided to try and go in a different direction

The day the world changed

Possible scenarios:

• Introduction of skills / powers
• Reincarnations start appearing
• The world starts ending

Story:

Follows the MC as they navigate this new world

• the people who use it to gain power
• the people trying to survive
• the people in denial
• whats the cause

Now that I have typed it out I realise there are a million already like this.