Affiliation: Member of the Armed Detective Agency Age: 22 Appearance: Characterized by his trench coat and bandages wrapped around his entire body. Ability: "No Longer Human" Effect: Completely nullifies any ability he touches with his skin. Strengths: No matter how powerful the attack or vicious the ability, it returns to a mundane phenomenon the moment Dazai touches it. Weaknesses: Since it is always active, it also nullifies beneficial effects from allies, such as healing abilities. Mafia Era: In the past, he handled numerous underworld incidents as a cold and ruthless executive of the Port Mafia. Parting with a Friend: Following the final words of his friend Sakunosuke Oda—the only person who truly understood him—to "be on the side that saves people," he left the Mafia for the Agency. He took in the protagonist, Atsushi Nakajima, guiding him to the Agency and serving as his mental pillar. Conversely, he maintains a harsh, distancing attitude toward his former subordinate from his Mafia days, Ryunosuke Akutagawa. He and his former Mafia partner, Chuuya Nakahara, are a legendary duo known as "Soukoku" (Double Black). Though they still fight like cats and dogs, their synchronization in combat is flawless.

Affiliation: Executive of the Port Mafia, the criminal organization that rules the city of Yokohama. Age: 22 Appearance: A petite young man wearing a black fedora, a choker, and a black overcoat. Complex: He is extremely sensitive about his short stature (160cm) and flies into a rage when teased about it. Ability: "Upon the Tainted Sorrow" Effect: Freely manipulates the gravity vectors (direction) and magnitude of anything he touches. Strengths: Possesses overwhelming physical destructive power, allowing him to fly by negating his own weight, deflect bullets, or effortlessly hurl massive debris. Worst Partner: He and Dazai have been at odds since they met at age 15. Whenever they meet, they fall into childish bickering. Legendary Duo: They share a history of annihilating an enemy ability organization in a single night and are feared in the underworld as "Soukoku." Absolute Trust: Chuuya can only use his life-threatening trump card, "Corruption," because Dazai's nullification can stop him from losing control. Despite their mutual loathing, they share perfect trust when their lives are on the line.

Affiliation: Member of the Armed Detective Agency (the practical backbone of the group) Age: 26 Appearance: Styled in an Inverness coat style with a characteristic brown casquette hat and cape. Motto: "All is well as long as I am fine." He is arrogant, selfish, and loves sweets. Useless in Private Life: He has an extreme lack of direction to the point where he cannot travel alone, unable to figure out how to ride a train or remember paths. Pride of the Agency: While usually childlike, when his comrades are in danger, he shows the cold composure of a man and a fierce determination to protect them. Ability?: "Super Deduction" Effect: By simply looking at a crime scene, he instantly sees the truth—the culprit, the method, and the location of evidence. The Truth: It is not actually an ability, but simply "overwhelming human genius (observation and logic)." However, he believes President Fukuzawa's lie and is convinced he is an ability user. Activation Condition: By putting on the "black glasses" given to him by the President, his ability (the genius brain he believes is an ability) demonstrates its true power. Absolute Devotion to Yukichi Fukuzawa: Ranpo's selfishness yields only to the President's orders. He loves the President like a father for recognizing his intellect as an "ability" and giving him a place to belong. He is held in absolute respect by all members of the Agency, including Dazai, who believe that "as long as Ranpo-san is here, any case can be solved."

Affiliation: Leader of the underground organization "Rats in the House of the Dead" and a member of the "Decay of the Angel." Age: Unknown Appearance: Black hair, wearing a white cotton hat resembling a Russian ushanka and a black cape. Ability: "Crime and Punishment" Effect: Long shrouded in mystery, its essence is the ultimate immortality and soul-transfer ability: "taking over the body and soul of the person who killed him (being reborn)." Strengths: While he was depicted as killing those he touched instantly, this occurs because the causality is established the moment the opponent harbors "some form of sin (such as murderous intent) and attempts to harm Fyodor." Killing him is the worst possible move, as it means falling directly into his trap.

Affiliation: Member of the "Decay of the Angel" and the "Rats in the House of the Dead." Age: 26 Appearance: Features an asymmetrical clown-like outfit, a white top hat, and a heart-shaped eyepatch. Catchphrase: Shouts "Quiz!" and poses absurd questions to those around him. Ability: "The Overcoat" Effect: Can connect the "inside" of the mantle he wears to another space up to 30 meters away. Strengths: By connecting spaces, he can pull a distant gun into his hand or teleport just his hand through a wall to attack an enemy from behind.

Affiliation: Member of the Armed Detective Agency (New Recruit) Age: 18 Appearance: Characterized by jaggedly uneven bangs and an outfit with a long, trailing belt. He fears others being hurt more than himself. He will face any terror if it means saving someone. Deep Trauma: Abuse suffered at the orphanage and the words "you have no value in living" are seared into his heart like a curse; he is constantly searching for his "reason to live." Earnest and Ordinary: As one of the few sane people in the Agency, he is daily at the mercy of eccentric seniors like Dazai and Ranpo. Ability: "Beast Beneath the Moonlight" Effect: Transforms into a ferocious, massive white tiger. Strengths: Possesses a tough hide that deflects bullets, claws that slice through iron bars, and an overwhelming "healing and regeneration ability" that allows him to regrow limbs instantly.