There are some dark anime that I advise you to watch, which are characterized by the nature of mystery and a complex plot that is definitely worth watching.
I will now mention five of those anime that did not get the attention they deserve.

parasite the miaximum
Number of episodes: 24 episodes
Anime classification: horror, action, science fiction, psychological, drama
the story
The story revolves around worm-like aliens that have come to invade Earth, and one of these worms descends from the sky on the home of a high school student named Shinichi. That worm almost entered Shinichi's mind to control his mind and control it, but it was unable to do so, so it entered his hand, so when Shinichi realized that that worm had entered his hand, he took the rope and pulled it on his hand for fear that it would go to his mind, So Shinichi became a normal human controlling his body and his mind, but the worm became controlling his hand and had supernatural abilities. The distinctive thing about the parasite anime is that it shows you how a person's personality changes from a gentle and weak person to a strong person who knows how to make the right decisions at the right time.

• demon corpse anime (shiki)   

Number of episodes: 24 episodes

Anime classification: horror, supernatural, mystery, drama​

the story

It's summer in a village called Sotobo that has more than 1,300 residents. Suddenly, for no reason, people start to mysteriously die after a new family moves into the village. What is the secret of this new family? Follow the anime to know the details.

• Claymore 

Number of episodes: 26 episodes

Anime rating:  Horror, action, shounen, drama

the story

In a world where people live with predatory demonic monsters called Yomo, and those monsters feed on humans and can mix with humans because of their ability to transform into human forms, and people decided to eliminate all those monsters, so they established an organization that contains half-human and half-Yomo warriors, and they are called by the name Silver-eyed witches

• Ergo proxy 

Number of episodes: 23 episodes 

Anime rating:  Sci-Fi, Mystery, Psychological

the story

After the catastrophe of the methane explosion that destroyed the world, all humans lived in a city called Romodo, and in it humans live with robots under a comprehensive administrative system and there is a division among people. There are two types of people, immigrants and citizens, and citizens are always of a higher degree than immigrants. The events of the anime take place after a series of crimes occurred by robots infected with a disease called Kojo, so a female investigator named Real Meyer begins an investigation to search for a solution to this case.

•  reLife

Number of episodes: 13 episodes 

Anime rating:  Romance, School, Slice of Life

the story

A 27-year-old man named Arataka Kaizaki, unemployed, lives a difficult life, and if he meets a man who invites him to work in a program called Nate, and gives him a mysterious drug that has the ability to make a person look younger in age, so he drank the medicine and took advantage of his young age to return to high school to complete his studies and start a new beginning .  

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