One night, as meteors streak across the star-studded sky, Shion Pavlichenko becomes a Contractor. Despite her brother's transformation, Shion's twin sister Suou continues to live a fairly ordinary life, attending middle school with her friends and getting caught up in the awkwardness of growing up. However, everything changes when her home is invaded by a masked man cloaked in black, destroying any sense of normality she once had. Revealed to possess latent Contractor abilities of her own, Suou is caught between family, friends, and her own sense of purpose as she ventures into the ruthless world of cutthroats and espionage that Contractors call home. Meanwhile in Tokyo, investigation surrounding Hell's Gate's sudden collapse is underway, and prophetic signs of doom point in the direction of a silver-haired doll. [Written by MAL Rewrite]

Losing a loved one is so painful that one may sometimes wish to be able to resurrect them—a weakness that the enigmatic Millennium Earl exploits. To make his mechanical weapons known as "Akuma," he uses the souls of the dead that are called back. Once a soul is placed in an Akuma, it is trapped forever, and the only way to save them is to exorcise them from their vessel using the Anti-Akuma weapon, "Innocence." After spending three years as the disciple of General Cross, Allen Walker is sent to the Black Order—an organization comprised of those willing to fight Akuma and the Millennium Earl—to become an official Exorcist. With an arm as his Innocence and a cursed eye that can see the suffering souls within an Akuma, it's up to Allen and his fellow Exorcists to stop the Millennium Earl's ultimate plot: one that can lead to the destruction of the world. [Written by MAL Rewrite]

Despite the recent Akuma attack, the members of the Black Order are in high spirits as they set about moving to a new base. Immediately upon his arrival, however, Allen Walker is suddenly called by the Central Agency and has his arm forcefully sealed by the Order. He is then led to a surprising meeting with his master, General Cross Marian, who reveals staggering secrets surrounding the enigmatic 14th Noah. A phantom thief incident, the arrival of a mysterious group of Exorcists, the death of an important comrade, and an all-out battle against the Noah Family—just what does this mean for Allen, Yuu Kanda, and the rest of the Order? This is but the beginning of a series of strange, seemingly unconnected events that lead to something far greater. [Written by MAL Rewrite]

"Toys" are powers bestowed upon those chosen to wield them, each having qualities that are unique to their users. Some of these individuals are born pure, using their powers to become detectives. Others bloom laced with poison and choose to become phantom thieves. These two opposing factions caused the formation of various detective academies around the globe—training detectives to fight and catch the phantom thieves. Sherlock Shellingford, Nero Yuzurizaki, Hercule Burton, and Cordelia Glauca form "Milky Holmes", a group recognized as the cream of the crop in the Yokohama-based Holmes Detective Academy. However, in a skirmish against the phantom thief Arsene, their Toys suddenly disappear, deeming them unfit to continue as detectives. Stripped of their prestigious life and thrown into a rundown attic, they face expulsion if they fail to regain their powers within the next three months. Tantei Opera Milky Holmes tells the story of a once-legendary group in their journey to recover their Toys, as well as attempting to continue their line of work without the powers that once defined their career. [Written by MAL Rewrite]