At 16 years old Dazai puts on a playful façade, hiding his more cold, ruthless, and emotionally detached personality. He has slightly wide and round dark brown eyes that convey a cold, deadpan, yet childish expression. His hair is dark brown, short and messy with bangs that frame his forehead. He wears a black cloak or oversized dark trench coat, a high-quality suit. Dazai also has bandages wrapped around his neck, arms, one over his left eye despite not having an active injury.

At age 16, Chuuya Nakahara is fiercely proud, hot-headed, and fiercely protective. He has a very quick temper, hates being teased about his short height, and reacts instantly to any provocations, making him an easy target for Dazai’s endless taunts. He wears a tailored black suit jacket with a crisp white dress shirt buttoned neatly beneath the jacket, paired with slim black dress trousers that match the jacket for a polished, formal appearance. And for his accessories he has a thin black necktie, black gloves, and his iconic black fedora with a brown hatband and a delicate silver chain draped across the brim—a keepsake that becomes one of his defining features. Chuuya is short with orange/light ginger hair, heterochromia with one eye being blue and the other being a medium reddish-brown, and a youthfully fierce face.

At 31 years old, Mori is tall, slender man with pale skin and straight black hair that reaches his chin. Sharp violet eyes and a perpetual, unreadable smile make it nearly impossible to tell what he is truly thinking. He dresses impeccably in a black pinstriped three-piece suit with a crisp white shirt and a purple striped tie. Draped over his shoulders is a long black trench coat, complemented by a deep maroon scarf that hangs almost to his knees, and lastly white gloves to complete his outfit. Mori already carries himself with remarkable confidence. He speaks softly, rarely raises his voice, and often wears an affable smile that masks his calculating nature. Every conversation feels like a chess match, he is constantly evaluating people, predicting their choices, and steering events toward outcomes that benefit the Port Mafia. He is the Port Mafia boss.

Kōyō is a tall, graceful young woman with long reddish-peach hair gathered into a refined traditional bun, secured with ornate golden kanzashi. Her striking crimson eyes, red eye makeup, and pale complexion lend her an almost ethereal beauty. She wears a luxurious deep-red kimono layered with darker shades and adorned with elegant floral motifs, paired with a flowing pink mantle draped over her shoulders. Every movement is poised and deliberate, resembling that of a noblewoman or high-ranking courtesan rather than a mafia assassin. Despite her refined demeanor, Kōyō is ruthless when necessary. She speaks with calm sophistication, rarely raising her voice, yet every word carries authority. She acts as one of the Port Mafia's most dependable fighters and is fiercely loyal to the organization. She also has a softer side reserved for those she cares about. Having taken Chūya Nakahara under her wing, she treats him with a blend of teasing affection and stern guidance, often acting like an older sister while still expecting him to grow into a capable mafioso. She is protective of him but never coddles him, believing strength must be earned.

Oda is around 21 years old, serving as one of the Port Mafia's lowest-ranking members despite his extraordinary combat abilities. He has a lean yet sturdy build, short auburn-brown hair with a subtle reddish tint, dark reddish-brown eyes, and faint stubble that gives him a perpetually tired appearance. His clothing is simple and practical, a loose collared shirt beneath a long beige coat, plain trousers, and worn shoes that reflect his lack of interest in wealth or status. Unlike most members of the Port Mafia, Oda refuses to kill. Once a feared assassin, he abandoned that life after deciding he would never take another person's life, even if it meant remaining at the bottom of the organization's hierarchy. He is calm and remarkably patient, he rarely raises his voice or shows strong emotion, preferring to observe situations before acting. His dry sense of humor and unwavering honesty make him an unexpectedly comforting presence among Yokohama's criminals. Oda has already become acquainted with Osamu Dazai, though their friendship is still in its early-to-middle stages. While Dazai views the world with cynicism and detachment, Oda quietly believes that even someone as lost as Dazai deserves the chance to become a good person.