Once upon a time, a Spider Demon was terrorizing a village and killing everyone who dared try to stop her. A brave monk managed to seal the Spider Demon and made sure no one could ever free her as long as he lived. Unfortunately, humans don’t live very long compared to youkai, and in our era, a young bookkeeper and his landlord granddaughter find a book with the offspring of said Demon; a cute tiny spider girl who looks completely defenseless. And, despite the warning in the book, they decide to raise her.

Wasurenagumo starts as a very heartwarming tale. After all, who wouldn't like to believe that all demons are just misunderstood cute creatures that need a bit of tender, loving care from humans to understand that we can all live together? However, you can imagine that it wouldn't be on this list if there wasn't some sort of plot twist and we can see how things start going a little bit wrong from the beginning. If you love tales where you start feeling uneasy without really knowing why before a spiral of bad things happens, Wasurenagumo will be perfect for a dark stormy night.

When Eiri Kurahashi starts working at an antique store, he never expected to find love. Specifically, he never expected to fall in love with a ghost girl whose reflection was caught in an antique mirror and who told him that the only way for her soul to be free was for a man to be willing to suffer the punishment that her murderer, artist Marchello Orlando, deserved for killing her. But that’s exactly what happened when he saw Cossette D’Auvergne’s reflection, and thus, Eiri decided to try to free her from her prison, even at the cost of his own soul.

Cossette no Shouzo has everything that makes a good gothic tale: love, betrayal, curses and the feeling that nothing is as it seems at first glance. You feel bad for Cossette’s fate, but at the same time can’t help but feel empathy towards the victims of her curse: they didn’t kill her and their only sin was to buy the objects that were splashed with her blood. Eiri’s love for Cossette seems pure at first, but when we discover he’s the reincarnation of her killer, we can’t ignore the possibility that he’s only attracted to her due to their entwined fates. All those different threads make this OVA a perfect treat for a horror night.

Not all vampires are completely evil. Miyu, for example, has been tasked with the mission to capture Shinma, the god-demons who feed on mankind’s spirit and try to destroy the barrier between the Darkness and the land of the living. Sure, she also needs blood to survive but when she exchanges blood with a human, she gives them an eternal happiness of sorts. As she masquerades as a normal human girl, she has to face the consequences of her mission when the Shinma go after those who are close to her.

Kyuuketsuhime Miyu is the second animated adaptation of the manga of the same name. The first one, also titled Kyuuketsuhime Miyu for some confusion, is a four-part OVA with some subtle differences in the characters, such as Larva, Miyu’s Shinma’s servant, always appearing masked. But both the OVA and the TV Series share the same dark atmosphere and the constant sense of tragedy: It's not only horrible because of what we see on the screen, but also due to what is implied. All the death, suffering, and horror that work on both levels make this story, in both formats, a great watch for a cloudy day.

Stop us if you have heard this one before: Two men walk into a bar where the bartender challenges them to a bet where they have to stake their lives. While it sounds like the beginning of a joke, this is how every episode of Death Parade begins: Two souls, with no memory of how they got to the bar, are pit again each other for a chance to earn a second chance to live. Quindecim, the bar, is really Purgatory and Decim the bartender is there to judge the true nature of those who reach his doors. There's only one problem: The system is rigged and it's not perfect. So sometimes, people can be sent to the wrong fate.

Death Parade is a very dark story which hinges completely in horror at a cosmic scale. The idea behind the plot is very simple: What if those in charge of weighing your sins simply don’t care about human morals and are so alien to our feelings that they can make mistakes or be lied to? What if your fate in the afterlife can be decided by something as seemingly random as a game of darts and you don’t even remember why you are there until the very last moment? This is the kind of series you should only watch if you are willing to have a nice insomnia-filled night.

The Mononoke are spirits who feed on negative human emotions. While now they’re practically extinct, during the Edo era they used to be quite common and would kill every human that entered their lairs. Fortunately for the people of the time, there's one man who possesses a sword that can exorcize the Mononoke as long as he knows their shape, their truth, and their reason for existing. This Medicine Seller, as he’s known by everyone, travels through Japan always ready to help those who need his help even if sometimes the ones who need him the most are the Mononoke themselves.

Mononoke takes a very good look at human nature and, sometimes, the reflection it shows us is not pretty. While it's a spin-off of another good horror series, Ayakashi: Japanese Classic Horror, the truth is that one can enjoy it on its own and it keeps a very steady pace in every episode. There are a lot of creepy moments even before each story's Mononoke is revealed and in the end, they all are very satisfying ghost stories which make this series a perfect addition to a sleepover party.

If you want a very special pet, you could try your luck in Los Angeles’ Chinatown. There’s a small store there where no matter what you want, the owner, Count D, will get it for you. However, there are two catches: The first is that most of those “pets” look like humans, ready to help their owners cope with whatever is missing in their lives. The second, much more dangerous, is that D will always give you rules: If you break them, he's not liable for anything that could happen to you. And people always break the rules.

Petshop of Horrors is a very interesting anthology series, as each chapter depicts a different client and not all of them break the rules out of malice or ignorance. Count D is a polite host who cares a lot for the animals both inside his store and in the world, but he doesn’t care that much for humans which put him into direct conflict with Leon, the police detective tasked with investigating the sometimes gruesome results of the broken rules. If you are a fan of the Twilight Zone, this is a great series that follows their tradition of great unexpected endings.

Mushi are spirits of nature that tend to swarm where humans live, becoming somewhat of a plague. The only people who can actually see them and thus make sure that both mushi and humans manage to get out of said entanglements alive are the Mushishi. Ginko is one of them and he travels all over Japan helping those who need his abilities. Most of the time, the mushi are not evil; they are only trying to survive and, unfortunately, their feeding habits can endanger humans, like those who eat memories or heat, for example, but they can also end up swallowing the person whole and turning them into mushi too. Ginko, at times, has to face that there are people not even he can save.

Mushishi is another story where the horror is slow-building. Yes, there are some horrifying scenes on screen, but many of the most terrible stories are when we start thinking about what it means for those living in that universe. Normal things like sitting down to rest in the shade, or watching rainbows can become deadly and unlike other demons and spirit stories, it’s not due to some moral failing of those who become affected. It could happen to anyone. So while the stories might end, the uneasy feeling of paranoia can stay with the viewers for a long, long time.

Is there anyone you really hate? Someone who has hurt you so much that you don’t care what happens to you as long as they are punished with eternal pain? If so, there’s one way to get revenge: visit the site Hell Correspondence, a site that only appears at midnight and only to those who feel a grudge so powerful that it will call the forces of Hell to your side. If you visit the site and then write the name of that person, Ai Enma, the Hell Girl, will come to you and offer to punish them for you. She won't care if your grudge is justified or not, she will only give you a choice: Either let go of that grudge and live your life in peace or ask her to drag those you hate to hell. Just be aware that you will be paying with your soul.

Jigoku Shoujo has more straight horror than the previous stories on our list as we're witnesses to a lot of abuse at the hands of those who will be eventually punished. More importantly, each season gives us an ongoing arc in which we only get small glimpses of the plot while we get to meet every one of Ai’s “Clients” for the shorter episodes, so we have time to imagine what the end of the ongoing arc will be in our minds, and that only helps to build the tension. At the end of each episode, there is always that lingering feeling that maybe the victim deserved to go to hell, but it can’t be a victory when we know the same fate will befall Ai’s “Client”. And if you have the habit of browsing the net at night, after watching the show, your midnight browsing can become a bit unsettling.

The students of St. Marguerite Academy have the peculiar habit of retelling horror stories and urban legends, to the point that some of them have ended up becoming part of the school tradition. One of them is that a foreign student with black hair will bring about many misfortunes, which is why when Kazuya Kujo—the third son of an imperial Japanese soldier—arrives at the school, he ends up ostracized by most of his classmates. Still, he doesn't quite mind, as that leads him to meet Victorique, a girl who looks like a porcelain doll and seems never to attend class, being more interested in solving mysteries both at the academy and at the nearby city.

Unlike other series on this list, Gosick has no supernatural elements. But that doesn’t stop the scares: The atmosphere surrounding St. Marguerite Academy is slowly but surely becoming more and more claustrophobic as the murders pile up and the whole country of Sauville is gearing towards war. The fact that the whole world is in the brink of World War II doesn’t really help when we remember what happened to Europe then. Every murder is shown in gruesome detail and we're constantly reminded that the worst monsters we can find are usually human. A great series if what you love is psychological horror and some gorgeous Victorian aesthetic.

Have you ever thought about becoming immortal? Living forever and never fear injuries or death? There are people who would kill for the chance, but Yuta is not one of those. He became immortal completely by accident when he unknowingly ate Mermaid Flesh. The problem is that mermaid flesh is so powerful that it can grant immortality, but most of the time, it causes either death or a painful transformation into a “Lost Soul”, an immortal monster that only lives to kill. Yuta was one of the “lucky” ones, but after 500 years, he is bored of life, and only wants to find a mermaid that can teach him how to die. He’s not alone anymore, as he rescued a young girl named Mana who was raised by mermaids in order to be killed, but Mana also wants to be mortal again.

Mermaid Forest is one of the lesser-known works by Rumiko Takahashi, the author behind comedy superhits such as Ranma ½, Urusei Yatsura and Rinne. No one expected her to be so good at horror, but the truth is that Mermaid Forest is one of the most chilling stories one can find. Immortality is shown to be incredibly lonely, as everyone Yuta loves dies. And Yuta is not only fortunate when he finds Mana, but also because in his long life, he has managed to stay sane, something other immortals he meets haven’t managed. If you haven't watched Mermaid Forest, be ready for a treat of intrigue, suspense, and horror that will make you appreciate your loved ones even more.