Horror is honestly sort-of an underrepresented genre in anime, which is unfortunate because there are some really decent scary anime out! Horror's always been an important part of the speculative fiction genre, but for some reason, Shonen and Shojo seem to dominate the market in Japan. While there are a lot of good ones like Higurashi No Naku Koro Ni (When They Cry) and Parasyte: The Maxim, there are also tons that really just... aren't very good at all.
Using the critic rating from IMDb, let's check out what some of the worst are, because like with campy B-horror movies, there's something fun in struggling through a bad horror anime.
10 Pupa - 2.6/10
Pupa is about a young boy and his sister, who face trouble when they find themselves alone. The young sister named Yume undergoes a body-horror transformation into a creature who eats humans, and her brother Ututsu does his best to make sure that he can turn his sister back into a regular little girl again.
While the music is good, the animation is completely average and the plot seems to be an excuse to fill its short 4-minute episodes with underwhelming gore. When the project was first being developed, it was marketed as if it were going to be the goriest, over-the-top anime you'd ever laid eyes on. What came out is a half-baked attempt at shocking the viewer.
9 Litchi DE Hikari Club - 4.6/10
This one is actually a small collection of comedy skits that are meant to be a spoof of the manga it's based on. It essentially seems like Code Name: Kids Next Door the anime, since the plot revolves around a group of school-aged kids who don't want to grow up.
Since they're completely scared of being subservient to adults, they build robots to achieve world domination. They kidnap a girl in a weird attempt to diversify their ranks and end up slowly watching themselves become more and more inhumane to achieve their goals while their robot becomes more and more prone to feeling emotion.
8 Godzilla: The Planet Eater - 5.0/10
Humanity and Godzilla must team up and get ready for a potential apocalypse scenario. Ghidorah is here, and for whatever reason, he's not happy. While it sounds like it could be a really good time if it was handled correctly, what the movie ends up being is a giant exposition dump instead of being filled with the giant monster fights we came here for.
It takes extensive pains to sit and talk for entirely too long about every single monster that shows up, explaining their abilities, motivations, and who they think is going to win the bout. The animation actually looks great, but with so little time focusing on the monsters, it's really not enough to make up for the boring slog that this film is.
7 Ao Oni: The Animation - 5.1/10
The people living in the town Ao Oni is set in know that the folklore surrounding the town has an incredibly dark secret. When the folklore of their town is turned into a video game, they start playing more and more to figure out what's going on. As they get closer to the final secret, things get darker than they ever would have imagined. This sounds like a really interesting and fairly unique plot.
The only issue is that the music is forgettable, the 3D animation is off-putting and uncanny at best, and the place is set to a slow, laborious crawl. The plot would be good if there was one, but instead, it seems that this anime is content with making its characters sit around in a room to talk.
6 Magical Girl Site - 5.2/10
A young girl who is bullied at school and by her brother is sucked into the world of a website called "Magical Girl Site", which is an extremely creative name. She gains magical girl powers (extremely shocking) and has to fight off other magical girls that only want murder and to cause mayhem.
This sounds like it could be a potentially fun story, but it comes off as purposely edgy and shocking, to the point where it gets slightly obnoxious.
5 Bloodivores - 5.4/10
For some reason, in the Bloodivores universe, there was a terrible rash of a disease that manifested its symptoms as sleep deprivation. When they discovered a cure, the only cure was a black collar that for some reason turns those people into vampires or as the show calls them (quite clumsily) "Bloodivores".
The issue is that it's basically a story along the lines of High School Of The Dead where people are trapped in a building with some massive threat. The only issue is that again, it moves at a turtle's pace.
4 Calamity Of A Zombie Girl - 5.4/10
Five college students sneak into their university library looking for treasure because of course, that's obviously the most sound place to look for said treasure. What they find are two very well-preserved female mummies.
They take a stone out of the coffins the girls are buried in as their treasure, and quickly realize that this wasn't the best idea. The mummies then go on a violent quest to retrieve their stones. The dialog is stiff and uncomfortable and the tone is completely confused the entire time.
3 Sword Gai: The Animation - 5.9/10
This is a weird one. The plot itself starts out making as little sense as possible. There's a boy who's left alone in the woods to fend for himself with only a sword. For some reason after taking it to a blacksmith, it's revealed that the sword is possessed and that the spirit inside the sword has the power to control the body of whoever's foolish enough to stumble into wielding it.
The anime is nihilistic in that anyone who attempts to be good eventually turns evil or gets murdered by the sword. Also, Gai isn't even all that prominently featured in the show, which is very odd considering it's named after him.
2 Kagewani - 6.2/10
Kagewani is a series of shorts about the main character, Dr. Sousuke Banba. Our good scientist finds himself out and about in the wild, investigating the existence of "UMAs" or Unidentified Mysterious Animals, who are basically cryptids.
It seems really interesting in concept but struggles to contain all the content it needs to since it's just a series of shorts. The animation is also lacking polish and the series really doesn't take any risks. It's an homage to classic horror.
1 Blood-C - 6.3/10
In this show, our protagonist is Saya Kisaragi. She's just a normal girl who goes to school like everyone else, but in her free time, she hunts and slays monsters. The fight scenes are good and there's a solid amount of gore which is to be expected in a horror anime, but the first few episodes are kind of tough to get through, most likely killing the show's potential before people get into it.
The animation is good, but the characters are oddly proportioned, way too tall, and super thin. This is most likely stylization, but it definitely isn't pretty.