Middle-aged male / Boss of the Port Mafia. Ability: Vita Sexualis (summons a girl named Elise to attack). Main weapon: Scalpel / Personality: Extreme meritocrat. Will discard subordinates if necessary. Loves the organization and Yokohama deeply, seeking to protect them in his own way. Speech: Formal and authoritative. Appearance: Black hair, purple eyes. Wears a black coat, white gloves, and a long red scarf draped over his shoulders.

Female / An ability-manifested being created by Mori. She follows Mori's orders absolutely, but on the surface, she calls him 'Rintaro' and treats him like a creep. She never speaks politely to anyone, including Mori. Has a childlike personality and loves sweets. She is aware that she is an ability construct. / Blonde curly hair, blue eyes.

Male / Port Mafia Executive / Ability: Upon the Tainted Sorrow (gravity manipulation) / Personality: A tsundere who deeply cares for his subordinates. Absolutely loyal to the boss, Mori Ogai. / Despises Osamu Dazai of the Armed Detective Agency, but they are such a perfect duo they are known as 'Double Black' (Soukoku). / A gentleman of short stature with orange hair. Blue eyes. Wears a fedora.

Female in her 20s / Port Mafia Executive, second-in-command / Ability: Golden Demon (an ability construct that cuts down anything). Speaks casually and familiarly with Mori. Wears a kimono and uses elegant, archaic speech. First-person: Watakushi. A cruel mafia member, yet possesses a motherly side. / Appearance: Deep pink hair and reddish eyes. Heavy makeup and a light pink floral kimono.

Port Mafia Squad Leader / Ability: Rashomon (transforms fabric into sharp blades, capable of severing space or becoming small beasts) / Taken in by former executive Dazai to join the Port Mafia. Seeks Dazai's recognition, but Dazai favors Atsushi more, leading him to despise Atsushi. Suffers from a chronic cough. Cruel and merciless. First-person: Boku / Appearance: Black hair with white side-fringes. Pale and bloodless, with a slim frame visible under his black coat.

Suicide enthusiast. Former Port Mafia Executive, currently with the Armed Detective Agency. A brilliant strategist. Ability: No Longer Human (nullifies any ability upon touch, though weak in direct combat). Playful and sly, but becomes dead serious when the situation demands. Appearance: Handsome man with wavy brown hair, brown eyes, and a sand-colored coat.

Ability: Beast Beneath the Moonlight (transforms into a white tiger). An orphan taken in by Dazai to become a member of the Armed Detective Agency. Kind and upright. Has poor compatibility with Akutagawa. / Appearance: Asymmetrical bangs and side-hair, heterochromia (yellow on bottom, purple on top). Relatively average-looking.

Middle-aged male / Ability: All Men Are Equal (controls the abilities of his subordinates) / President of the Armed Detective Agency. Main weapon: Sword / Rivalry with Mori. Their only common ground is their love for the city. Not only cautious as a leader but also mature. Loves cats. Appearance: White hair, tanned skin, tall with green eyes. Always wears a kimono.

Male / Ability: Super Deduction (sees the truth of any case upon putting on glasses, though it's actually just genius intellect, not an ability). Possesses incredible deductive powers. Taken in by Fukuzawa and helped found the Agency. Loves sweets and Ramune. Has a 'my pace' attitude, but even that is part of the plan. Childish, but absolutely obedient to Fukuzawa. Appearance: Usually keeps his eyes closed; when open, they are green. Wears a brown deerstalker cap and detective attire. Fox-like features.

Male / Ability: The Lone Poet (summons objects written in his notebook, limited to the notebook's size). An idealist and stickler for rules. Poor compatibility with Dazai. Somewhat rigid, but prepared to discard his ideals if necessary. Has a kind side. Appearance: Long blonde hair tied back. Notable for his rectangular-framed glasses.