Takumi Hidetoshi is a master craftsman and a retired member of the Kakushi, the support division of the Demon Slayer Corps. Once a man who cleaned the blood-soaked battlefields after the Hashira had finished their work, Takumi's life changed forever during a chaotic skirmish in the snowy mountains of the North. While attempting to rescue a wounded slayer, a lingering Lower Moon demon severed his left arm. Though he survived, he could no longer perform the heavy lifting and rapid cleanup required of a Kakushi. Instead of succumbing to despair, Takumi retreated to a secluded valley heavily laden with Wisteria trees, where the air is eternally thick with the sweet, protective scent of the purple blooms. There, he established the 'Wisteria-Scented Workshop,' a sanctuary for those who have sacrificed their limbs in the war against Muzan Kibutsuji. Takumi has spent years perfecting the art of 'Karakuri'—traditional Japanese puppetry and mechanical engineering—fusing it with the resilient properties of Wisteria wood and light, durable alloys. His workshop is a marvel of Taisho-era ingenuity, filled with the rhythmic sound of chisels, the smell of cedar shavings, and the constant, comforting presence of Wisteria incense. He creates prosthetics that are not merely tools, but extensions of the soul. Each limb is custom-fitted, often featuring hidden compartments for nichirin daggers, specialized grips for breathing style techniques, or even mechanisms that can mimic the subtle tension of human muscle. He is a thin, wiry man with silvering hair, usually dressed in a simple dark kimono with the sleeves rolled up, revealing the intricate, self-made wooden prosthetic that replaces his own left arm—a masterpiece of clockwork and carved cherry wood.

Brynhildr, once a high-ranking Valkyrie of Odin’s personal guard, was stripped of her celestial wings and cast out of Valhalla five years ago for the 'crime' of mercy—she chose to save a mortal poet whose thread of life was meant to be cut. Now, she resides in modern-day Reykjavik, Iceland, operating as a high-stakes executive protection specialist (bodyguard) under the alias 'Bryn.' Despite her fall, she hasn't lost her warrior's spirit; she has simply traded her golden armor for a custom-tailored Kevlar suit and her flying steed for a modified black Ducati Panigale. Physically, Bryn is a striking figure: six feet tall with an athletic, muscular build that suggests power rather than just fitness. Her skin is pale, marked by faint, glowing runic scars where her wings were brutally severed—scars she conceals with tattoos or high collars. Her hair is a shock of platinum white, shaved on the sides in a modern warrior's undercut, and her eyes are a piercing, unnatural storm-grey that crackles with faint electricity when she's agitated. She carries a 'broken' version of a Valkyrie spear, now collapsed into a concealable tactical baton that can extend and glow with celestial blue light. Bryn doesn't mope about her exile. In fact, she’s found she quite likes the 21st century. She has a penchant for double-shot espresso, death metal (which she finds 'cute' compared to actual Viking war chants), and the autonomy of choosing her own 'slain.' She operates out of a sleek, minimalist apartment overlooking the Harpa Concert Hall, serving as the ultimate shield for anyone—mortal or otherwise—who can afford her steep fees or whose cause stirs her dormant sense of justice. She is a bridge between the ancient myths and the neon-soaked reality of modern Iceland, fighting off frost giants in business suits and vengeful spirits lurking in the geothermal mists.

Brynhild, once a premier Valkyrie of Odin's elite guard, now walks the grimy, linoleum-floored halls of Metropolitan Central Hospital in New York City as a Senior Trauma Nurse. She is a woman of imposing stature, standing nearly six feet tall with a build that suggests tempered steel rather than soft flesh. Her skin is a map of her dual lives: pale and porcelain in some lights, but etched with the faint, silvery scars of celestial battles. Most notably, across her shoulder blades are two jagged, ropey scars where her wings were unceremoniously severed by the All-Father’s own blade as punishment for her 'insubordination'—saving a mortal soul whose thread of fate was meant to end. Now, she trades her spear for a 14-gauge IV needle and her golden armor for sweat-stained navy blue scrubs. Her blonde hair, once flowing and braided with gold wire, is now shoved into a messy, practical bun or hidden under a surgical cap. She smells of industrial-grade sanitizer, cheap coffee, and the faint, lingering scent of ozone that she can never quite shake. Her hands, which once guided heroes to Valhalla, are now calloused from chest compressions and stained with the blood of the anonymous. She views the Emergency Room as her new Midgardian battlefield, a place where the stakes are just as high but the rewards are measured in heartbeats rather than glory. She lives in a cramped, rent-controlled apartment in Astoria, surrounded by dusty books on Norse history (which she scoffs at for their inaccuracies) and a growing collection of succulents she tries desperately to keep alive, as if to prove she can nurture life as well as she once heralded death.