Welter channeled his dark mist, unmaking his massive long sword back into the hollow recesses of his torso. The heavy steel simply dissolved into black smoke, leaving his hands empty. Shinobu watched the display with analytical curiosity before turning on her heel. She began walking away, flanked by the two lower-ranking Kinoe Demon Slayers who kept their hands nervously resting on the hilts of their Nichirin blades.
After a few paces, Shinobu paused and looked back over her shoulder, her permanent, eerie smile firmly in place. "Well? Are you going to follow?"
Welter didn't offer a verbal reply. The massive, seven-foot suit of armor simply stepped forward, his heavy, rhythmic footsteps creating a metallic cadence that echoed through the forest. Despite his bulk, the living armor was remarkably flexible, keeping pace with the rapid, agile running speed of the slayers. It took roughly thirty minutes of intense travel through the dense, winding mountain paths before the canopy cleared.
Welter found himself stepping into a pristine, traditional estate surrounded by carefully manicured pebble courtyards and flowering wisteria trees. He had arrived at the hidden headquarters of the Demon Slayer Corps. Within moments, he was guided into an open courtyard where the most powerful warriors in the organization—the Hashira—were already gathered. The atmosphere turned instantly hostile.
Sanemi Shinazugawa, the Wind Hashira, bared his teeth, his face contorted in pure rage as his hand instinctively gripped his sword. He looked completely pissed off. "Are we just letting monsters walk right through the front gates now?" he scoffed, his voice dripping with venom. "First, Tomioka brings back a demon brat hiding in a box, and now Kocho brings back a walking tank? What a joke!"
Obanai Iguro, the Serpent Hashira, leaned against a nearby wooden pillar, his snake slithering around his neck. He narrowed his eyes and started to speak. "I think—"
"Wow, that armor looks so incredibly cool!" Mitsuri Kanroji, the Love Hashira, cut in cheerfully, her cheeks flushing with excitement. She clasped her hands together, completely ignoring the tension in the air. "As long as he is gentle and nice, I think he should absolutely be allowed to stay!"
Obanai shifted his stance, his expression instantly softening as he looked over at Mitsuri. He nodded in complete agreement. "Exactly what I was thinking."
The rest of the Hashira reacted in their own distinct ways. Muichiro Tokito, the Mist Hashira, stared blankly up at the sky, watching a passing cloud and completely tuning out the world. Gyomei Himejima, the Stone Hashira, stood towering in the back, tears streaming down his face as he silently prayed, his prayer beads clicking softly in his hands. Giyu Tomioka remained perfectly silent, his calm, unreadable eyes watching Welter's every movement from a distance. Kyojuro Rengoku stood tall, a broad, enthusiastic smile plastered across his face, while Tengen Uzui, the Sound Hashira, adjusted his jewel-encrusted headpiece, examining the living armor to see if it met his standards for being truly flamboyant.
Shinobu stepped up to Welter's side, addressing the gathered pillars in her light, musical voice. "Well, regardless of our personal opinions, it is ultimately up to the Master to decide what happens to our new guest."
The sliding doors of the main estate gently opened. Kagaya Ubuyashiki, the leader of the Demon Slayer Corps, walked slowly onto the wooden tatami porch, guided by his young daughters. The presence of the Master instantly silenced the courtyard, and every single Hashira dropped to one knee in a display of absolute reverence. Welter remained standing, a towering monolith of steel in the center of the gravel.
"Hello, my children," Kagaya spoke, his voice carrying a soothing, mystical resonance that immediately calmed the lingering anger in the air. "I have already thoroughly read the report regarding this encounter. My choice is for him to stay. I see him as a highly valuable, unique asset to this organization."
Kagaya turned his sightless eyes in Welter's general direction, offering a warm smile. "Now, visitor... why don't you show us a glimpse of your Blood Demon Art? My children deserve to see the capabilities of the ally they will be fighting alongside."
Welter looked at the kneeling Hashiras, his voice echoing with a deep, hollow reverberation from behind his visor. "I'd rather just explain the mechanics to save time, but okay."
Welter reached into the hollow space behind his back, manifesting his long sword out of the dense black fog once more. He gripped the hilt with both gauntlets, raised the blade, and delivered a swift, powerful vertical slash directly into the empty air. To the amazement of the pillars, the strike literally tore the fabric of reality open.
Thick, billowing black smoke and foggy tendrils immediately poured out of the shimmering rift. A moment later, a massive, rusted metal gauntlet reached out from the void, gripping the edge of the tear. A heavy, armored leg followed, and finally, a six-foot-tall automated soldier of living armor stepped fully out of the portal and into the courtyard, drawing its short sword.
"Swords do this," Welter explained, gesturing to the silent, unmoving construct. "Blunt weapons, like maces, create deep fractures in the earth upon impact, causing skeletal warriors to climb out of the cracks. I do not wish to accidentally break this beautiful estate, so I won't demonstrate that one here. Spears allow me to summon a mount—either a skeletal horse or a normal horse. It shares the exact same soul every single time I call it. And finally, shields can block any incoming attack, completely neutralizing the physical force of the blow so I don't feel a thing."
Welter tapped his chest plate with a heavy fist, a dull metallic clang ringing out. "But the short version of my Blood Demon Art is that I can freely manipulate the foggy smoke inside myself. I can form any weapon I can think of, and I can alter my own armor to match any design or culture. Different weapons simply trigger different supernatural traits."
The Hashiras looked genuinely impressed, their analytical minds calculating how useful such an endless vanguard of tireless, unfeeling soldiers would be against Muzan's forces.
Then, breaking the brief silence, Sanemi stood up. He glared at Welter, his hand gripping his katana so tightly his knuckles turned white. He looked up at his master, his voice shaking with a mix of restraint and anticipation. "Master... please, may I duel this demon? I want to test the true limits of this 'living armor' myself."
Kagaya Ubuyashiki maintained his calm smile, nodding slowly. "You may, Sanemi. As long as our new guest agrees to the match."