The idea of the supernatural is really terrifying. For example, in the 'Crying Baby Bridge' legend, the thought of a ghostly baby crying from beyond the grave is spooky. Also, the lack of control. When faced with something like the 'Slit - Mouthed Woman' in the story, the victims have no real way to defend themselves or escape easily.
The mystery surrounding these urban legends is a major scary factor. We don't know if they are based on some real events or just made - up tales. And the way they play on our basic fears, like the fear of the dark in the 'Black Eyed Kids' legend where they often appear at night or in dimly lit areas, makes them even scarier.
The sense of the unknown. In many Japanese urban legend horror stories, there are no clear explanations for why these things happen. For the Aka Manto in the toilet, there's no backstory as to why he is there or what his true motives are. This lack of knowledge makes the stories even scarier as our minds start to fill in the blanks with the most terrifying possibilities.
The isolation is a really scary element. When you're in an abandoned place like an old building or a tunnel, you're cut off from the normal world. There's no one to help if something goes wrong. Another is the unknown history. You don't know what happened there in the past, whether it was a place of death or some kind of cruel experiment. The strange noises also add to the horror. They can come from anywhere, and your mind starts to imagine all kinds of terrifying things that could be making those noises.
The unknown. In the city, there could be all sorts of things lurking in the shadows. Maybe it's an abandoned building with a dark past or a hidden underground space. You don't know what you might stumble upon. It could be a homeless person with malicious intent or some kind of supernatural presence. Like in one story, a camper found a hidden basement in an old building he was camping near, and when he went down, he felt an overwhelming sense of dread for no obvious reason.
The Bunny Man Bridge legend is quite frightening. It's set near a bridge where people claim to see a man in a bunny suit, often carrying an axe. Some say that if you cross the bridge at night, he'll chase you. There are various versions of how this legend started, but the idea of being chased by a menacing figure in a bunny suit in a dark, secluded area is truly terrifying.
The unknown is the scariest. In 'as is horror stories', things are often left in their natural state, so you don't really know what's lurking in the shadows or what's causing those strange noises. It's that sense of not having all the answers that makes it terrifying.
Isolation is also a key element. When characters are alone in a spooky place, like an abandoned asylum in one of the stories. They have no one to turn to, and that makes the situation even more terrifying as the horror unfolds around them.
The unknown is one of the scariest elements. When things are not clearly defined, like a strange figure in the fog in some stories from '1001 horror stories', it makes our imagination run wild. We start to create the most terrifying scenarios in our minds.
The scariest element could be the sense of the unknown. For example, in many stories, there are strange noises or happenings that the characters can't explain. It's that not - knowing what is causing the fear that really gets to you.
The isolation in many of the stories is really scary. Like when a character is alone in an old, abandoned building, cut off from the outside world, and they start to feel like they're being watched by something malevolent. There's also the fear of the supernatural, such as ghosts or demons that defy the laws of nature. This makes the characters, and the readers, feel powerless against them.
The sudden movement of the LPS toys when they're not supposed to be able to move is really scary. It goes against what we know about them as inanimate objects.