The series is about a demon, Neuro Nogami, who feeds on mysteries, and has come to the human world after eating all the mysteries in the demon world. But as a demon, he cannot act overtly.The first thing he does is force a high school girl to become a detective, while Neuro acts as her assistant. While it appeared to be a mystery series early on, the author has described it as "a straight forward entertainment book wearing the skin of a mystery."

Neuro Nougami
Seiyu: Takehito Koyasu
The title character of the series, Neuro is literally a detective from Hell (Makai). He looks for mysteries and the labyrinthine mind for sustenance. As he explains it, when he dismantles the mystery and strips the culprit of all of their defenses, that releases the negative energies that caused the culprit to commit the crime, which he then consumes. He came to the human world in search of the Ultimate Mystery, as all of the mysteries in Makai were bland and repetitive. Once in the human world, he adopted Yako as his assistant, and began to solve mysteries. He does this because there's a rule in Makai that when the Makai inhabitants go to the human world, they must keep a low profile. In public Neuro makes Yako act as the detective, while he acts as her assistant, even though Neuro is actually doing all the detective work (though Yako occasionally figures things out herself as well). In the human world Neuro needs to sleep for three hours a day, which he spends on the ceiling. According to Neuro "Shouki is like Oxygen to a demon" and hot springs are formed when excess Shouki comes to the surface, so the best place for him to sleep is a hot spring. As Yako points out, he comes to the human world because eating is more important to him than oxygen.

Yako Katsuragi
Seiyu: Kana Ueda
Yako is a 16-year-old high school girl and the very first character introduced in the manga. She meets Neuro when he appears, desecrates her father's shrine, and promises to help solve the mystery of his death. She has an insatiable appetite (which people often associate her with), and a knack for understanding human psychology that occasionally provides Neuro with information he is unable to obtain because he is unfamiliar with how humans operate. She also is Neuro's cover, pretending to be the detective while he acts as her assistant. Neuro enjoys abusing her, though he does compliment her at times of success, albeit through minimizing comments.

Eishi Sasazuka
Seiyu: Koji Yusa
Sasazuka is one of the two police officers assigned to solve the mystery of Yako's father's death. After Neuro solves the case of Yako's father's death, Sasazuka gives them access to crime scenes, arrests the culprits as Yako points them out, and deals in the aftermath. Sasazuka appears listless and disinterested at times but he has an agile mind, acts very quickly in any emergency, and is an excellent shot. Usually he takes a kind and cooperative attitude toward Yako, but appears to be somewhat suspicious about Neuro. A former classmate of Usui and Tsukushi's, he joined the police force to investigate X.

Jun Ishigaki
Seiyu: Kosuke Toriumi
Ishigaki is a young police officer. After the mystery of Yako's father's death, Ishigaki becomes Sasazuka's new partner. As a typical modern young man, Ishigaki is flippant, careless, and has low self-respect. He idolizes Sasazuka, but does not share his feelings that citizens like Neuro and Yako can interfere with police business. He is very interested in all kinds of toys and models and is shown regularly collecting them.

Shinobu Godai
Seiyu:Hiroyuki Yoshino (anime), Kisho Taniyama (radio drama)
Godai worked for a small finance house with criminal connections. After Neuro won a bet against the members of the finance house by solving their boss's death, Godai was forced to work for Neuro. Neuro also won their office in the bet. He is the jack of all trades for the detective's office and is sometimes referred to as "Neuro's second slave". Godai is quick-tempered and yells a lot, but has also been shown to be methodical, responsible, and trustworthy. He has a fondness for cars and was upset after his was wrecked during the HAL arc.

Akane
Akane is a corpse in the wall of the office Neuro took over, who is shown only as a detachable braid of hair, which functions like a hand. Neuro offered to make Yako brush and care for her in exchange for secretarial work. Akane can be taken from the office for short periods of time and can also merge with Yako's hair to make it longer, which not only gives Akane control over Yako's natural hair, but if left merged for too long, would make Akane and Yako switch places completely. Akane later appears (as a braid) attached to Yako's new cell phone.

Aya Asia
Seiyu:Minami Takayama
A world-class idol who comes to Neuro's office to hire the detective team to figure out who murdered her managers/friends. Her plan appears to be foiled when both Neuro and Yako incriminate her on television. The publicity of her case earns Yako a somewhat notorious reputation.

X
Seiyu:Romi Paku
X (or Sai) is a mysterious human with supernatural powers. He believes himself without an identity and, in a desperate attempt to find one for himself, starts taking people apart and studying their insides to find out what gives someone an identity. He is able to alter his own cellular structure to his convenience and take on the appearances of other people, though doing so makes him lose his memories, presumably creating and compounding his initial problem. Also, even though he seems to have great control over his ability, it isn't perfect; once, when he was in the form of a dog, when he changed back to his human form, he still had the ears and lower body of the dog, making him look similar to a satyr. He has also said that he hates being in boxes, implying that he was once a laboratory subject. He was suspected of being the murderer to Yako's father; however, he said that he couldn't remember whether or not he had killed him, as the majority of his memories were lost.
X is actually a modified prototype clone made by Sicks, called "Experiment.11". A female as of birth 17 years ago. Her surrogate mother is killed immediately after her birth. For 5 years after birth she is nurtured in reinforced glass confines. She is then sent out to the into the world in order to get data on cell mutation and social adaptation, after that arrangements are made to retrieve her. But the person in charge of retrieving X, Imina, supports X thus rendering the recapture impossible.
After she was recaptured by Sicks, she returned to the life of a guinea pig. Her cells are also being made use of.

Hisanori Hayasaka
Hayasaka Yukinori's older brother. He smuggled in weapons and drugs that he was supposed to be bringing in for the company he worked for, but was actually planning to kill his superior, Mochizuki, in order to take over. Neuro managed to stop him from doing so. Later, he and his brother started "Smiling Face Ltd.", a company front for smuggling drugs and weapons as well as black-market trading of organs and other illegal things. Hisanori is alway seen smiling.

Yukinori Hayasaka
Hayasaka Hisanori's younger brother, nicknamed "Yuki". He is originally seen wearing a heavy winter coat at all times, which he uses to hide weapons. He has a great deal of respect for his older brother.

Eisuke Harukawa
Genius neurologist and computer scientist at Sakuba University. He is the creator of HAL and the Denshi Drug. After finding out that the Denshi Drug had been used by HAL on hundreds of people (rather than his two selected test subjects) he was killed by HAL's three supercomputer guardians (Tatsuo, Shiho, and Hiroto).

Yuya Higuchi
Seiyu:Nozomu Sasaki
A nineteen-year-old hacker/detective who works for the police. Although he is far-sighted, he only wears his glasses when using the computer, letting them rest on his forehead the rest of the time, because Usui wears glasses as well. He considers himself responsible for his parents' deaths. During the HAL arc, he was infected with the Denshi Drug to become one of HAL's guardians, although the infection was incomplete due to the fact that he was wearing glasses at the time.

HAL
AI created from a copy of Harukawa's brain. Created to help Harukawa with his project to recreate the brain of a person from scratch. However, seeing Harukawa's methods and intelligence as far inferior, he took it upon himself to go to much greater lengths to continue the project. While almost invincible in the digital world, the Denshi Drug was used by HAL to brainwash people into protecting the supercomputers that maintained his system.

Sicks
The man referred to as "absolute evil" by Kasai. Sicks is also a member and potentially the current head of the "New Bloodline," a group that distinguishes themselves from humanity by extent that they have bred 'evil intent' into their bloodline over the last 7000 or so years and whose aim is to extinguish humanity from the planet

Zenjiro Kasai
Fire-obsessed member of the New Bloodline. Infiltrated X's group as a spy and was instrumental in X's capture by Sicks.

I
X's assistant. Formerly a government-sponsored terrorist who brought down planes, named Imina.

Andrew Sixson
British investigator dispatched by the international police agency. Acquaintance of Usui's, from when Usui was an exchange student in England. Sixson is capable of memorizing vast amounts of information extremely quickly, picking out a single bit of information by listening to multiple radio stations at once, or reading through a stack of papers in an instant. He is an distant relative of the New Bloodline. He was kidnapped, tortured, had the skin peeled off his face, and was killed by Sicks' underlings so that Sicks could pose as a member of the police.

Tetsuyuki Homura
Seiyu:Yuuichi Nakamura
An early victim of the Denshi Drug (which caused him to become a crazed arsonist wielding a flamethrower that resembled a fire extinguisher.) Homura is also Kasai's nephew, although it is unclear if he is actually a member of the New Bloodline or not.

Tatsuo Koshiba
Research assistant at University. One of HAL's guardians. His criminal desire was to hit things. Was killed by HAL for his incompetence, and replaced by Yuya Higuchi.

Shiho Ezaki
Seiyu:Shiho Kawaragi
Research assistant at University. One of HAL's guardians. Her criminal desire was to put holes through things.

Hiroto Asanaga
Seiyu:Anri Katsu
Graduate sudent at University. One of HAL's guardians. His criminal desire was to shoot things with guns.

DR
Short for "DRagon". Member of the New Bloodline, from a specialized line with the ability to control water. With some of X's cells transplanted into him, he was capable of transforming his hand into claws..

Coming Soon

Coming Soon

Coming Soon