Shamans are extraordinary individuals with the ability to communicate with ghosts, spirits, and gods, which are invisible to ordinary people. The Shaman Fight—a prestigious tournament pitting shamans from all over the world against each other—is held every five hundred years, where the winner is crowned Shaman King. This title allows the current incumbent to call upon the Great Spirit and shape the world as they see fit. Finding himself late for class one night, Manta Oyamada, an ordinary middle school student, decides to take a shortcut through the local cemetery. Noticing him, a lone boy sitting on a gravestone invites Manta to stargaze with "them." Realizing that "them" refers to the boy and his ghostly friends, Manta flees the terror. Later, the boy introduces himself as You Asakura, a Shaman-in-training, and demonstrates his powers by teaming up with the ghost of six-hundred-year-old samurai Amidamaru to save Manta from a group of thugs. You befriends Manta due to his ability to see spirits, and with the help of Amidamaru, they set out to accomplish You's goal of becoming the next Shaman King. [Written by MAL Rewrite]

In Japan, the country that inspired the slogan "Born to be Mild," the blood of young men still runs hot. In the old days they'd go off into the country and hack each other up with swords, but these days, what with school, that isn't very practical. So some of them do something very un-Japanese. They strap on a big bike, roar around annoying people, and pound anyone they consider dishonorable. Now meet Eguchi Yousuke, leader of a high-school Biker gang AND the school's handicrafts club. Which means he divides his time between fistfights and fancy needlework. And if you think he's weird, wait until you meet the rest of his gang...

Yako Katsuragi is an acclaimed high school detective, who, despite her young age, has solved many cases. In fact, there seems to be no case that she can't solve, or any culprit that escapes justice. But within the walls of her detective agency lies the secret to her prolific crime-solving skills: the cases are actually solved by her assistant, Neuro Nougami. However, to call Neuro an ordinary man would be incorrect. In reality, he is a demon, who came to the human world in search of the ultimate mystery, having already solved every mystery in the demon world. With Yako as his proxy, he feasts on the negative energy released by humans when they commit crimes. Thus, he promises to help Yako solve the mystery of her father's death. But to do so, he must avoid drawing too much attention to himself, which is why Yako plays the role of the detective. Majin Tantei Nougami Neuro follows this unlikely duo as they solve case after case to satisfy Neuro's ravenous appetite and Yako's desperate search for the truth of her father's death.

The limited-edition of the 26th manga volume will include an anime adaptation of the popular special flashback chapter "Uchi ga Kita Machi" (The Town Where I Arrived). The story reveals how Haruto, Akari, and Takashi first met during childhood, and serves as a prologue to the TV anime. The 27th limited-edition manga volume will include a special anime episode produced in full cooperation with Seo Kouji. This OVA will be the animation of the end of the manga. (Volume 27 is the final volume of the long-running series.)