The ceremony room was exactly as Amane had described—spiritually pure in a way that even Su Chen's heavily modified perception could appreciate. The space had been maintained for generations as a sanctuary for the Ubuyashiki family's most sacred rituals, its walls inscribed with protective sutras and its floor composed of blessed hinoki cypress that released a subtle fragrance promoting mental clarity.
Su Chen directed the arrangement of the space with practiced efficiency. "Xiao Yi Xian, establish a toxin barrier around the perimeter. Nothing too lethal—we want to contain any parasitic fragments that might attempt escape during extraction, not accidentally poison everyone in the estate. Saeko, position yourself at the doorway. No interruptions once we begin, regardless of what sounds emerge from this room. Esdeath, maintain a time-dilation field around the chamber—compress external time so that four hours inside passes as thirty minutes outside. The Hashira are anxious enough without making them wait half the night."
Each team member moved to execute their assignments without question. The Hashira who had insisted on observing—Gyomei, Shinobu, and Sanemi—watched with fascination as Su Chen's companions demonstrated capabilities that shouldn't exist in their world.
Xiao Yi Xian's toxin barrier manifested as a shimmering rainbow film that coated the room's walls. Shinobu approached it cautiously, extending one finger to test its properties. The moment her skin made contact, she jerked back with a sharp intake of breath.
"That's... it's not just poison," Shinobu said, her medical expertise immediately recognizing something beyond normal toxicology. "It's conceptual. It's telling my cells that existence outside this room is forbidden. Even touching it briefly, I can feel my body instinctively recoiling."
"Correct," Xiao Yi Xian confirmed. "Anything attempting to cross that barrier without authorization will find its biological processes simply stopping. It won't experience pain or damage—it will just cease to function. That includes parasitic consciousness fragments trying to escape during extraction."
Esdeath's time dilation field was less visually obvious but no less impressive. She touched her hand to the room's central pillar, and frost spread across its surface in intricate patterns. The temperature didn't drop—instead, the very flow of time became sluggish, like reality itself was moving through cold syrup.
"Time ratio is set to eight-to-one," Esdeath reported. "Four hours inside, thirty minutes outside. I can maintain this indefinitely with my current reserves, but let me know if you need adjustments."
Gyomei's blind gaze tracked each phenomenon with his spiritual perception, his expression showing profound confusion. "These techniques... they violate every principle of combat and ability I've encountered. The poison doesn't work through biological mechanisms—it imposes concepts through will alone. The time manipulation isn't affecting temperature or movement speed—it's actually altering causality's flow rate. How is any of this possible?"
"Different world, different rules," Su Chen replied while arranging formation materials in specific geometric patterns across the floor. He was using a hybrid approach—combining Perfect World's formation theory with principles adapted from the Demon Slayer dimension's spiritual framework. "Your world has breathing techniques that allow humans to temporarily manifest elemental effects through perfected technique and willpower. That's already bending physical laws. My companions' abilities just bend those laws in different directions and to greater extremes."
He gestured for Kagaya to take position at the formation's center. "Master Ubuyashiki, please sit here and remove your upper garments. I'll need direct access to your spiritual channels, which means working through skin contact rather than remote manipulation."
Kagaya complied without hesitation, his trust in Su Chen apparently absolute despite knowing him for less than an hour. His exposed torso showed the curse's physical manifestation more clearly—dark veins spreading across his skin like a spider's web, concentrating most heavily around his heart and lungs. The pattern was clearly non-random, resembling a parasitic root system drawing nutrients from its host.
Su Chen activated his dual pupils to maximum perception, his golden eye revealing the energy flows sustaining the parasite while his silver eye mapped the spatial structure connecting it to Muzan's distant consciousness. What he saw confirmed his initial diagnosis but added disturbing details.
"The parasite is more sophisticated than I initially realized," Su Chen muttered, mostly to himself but loud enough that the observers could hear. "It's not just monitoring and feeding—it's actively manipulating your decisions through subtle emotional influences. Whenever you consider strategies that might genuinely threaten Muzan, the parasite generates sensations of doubt or anxiety. Not enough to be obvious, but sufficient to unconsciously steer your thinking away from optimal approaches."
Kagaya's expression showed dawning horror. "Are you saying that Muzan has been influencing the Corps' strategy through me? That our failures to eliminate him might partially be my fault?"
"Not your fault—Muzan's manipulation," Su Chen corrected firmly. "You're the victim here, not the perpetrator. And we're about to end his surveillance permanently. Now, the extraction process will be extremely painful. The parasite has grown into your spiritual foundation over generations—removing it is like pulling roots from soil without damaging the surrounding earth. I'll work as quickly as possible, but you will suffer. Can you endure?"
"I have endured this curse killing me slowly for my entire life," Kagaya replied with quiet strength. "Four hours of pain to end it is a bargain I accept gladly."
"Good answer," Su Chen approved. He placed his hands directly on Kagaya's chest, his fingers positioned over the parasite's main concentration points. "Beginning extraction in three... two... one."
Divine energy flooded from Su Chen's hands into Kagaya's body, golden light visible even through flesh as it traced the parasite's structure. The effect was immediate—Kagaya's body arched in pain, every muscle tensing as the foreign consciousness fragment recognized it was under attack and fought desperately to maintain its existence.
Sanemi started forward instinctively to intervene, but Gyomei's massive hand caught his shoulder, holding him back. "Trust the process. Master accepted this willingly."
Su Chen worked with intense concentration, using divine energy like surgical instruments to carefully separate parasitic tissue from healthy spiritual foundation. The parasite had grown sophisticated over centuries—it had intertwined itself so thoroughly with Kagaya's life force that extracting it carelessly would kill the host along with the invader.
But Su Chen possessed advantages the parasite hadn't anticipated. His experience with the T-Virus gave him understanding of how parasitic organisms integrated with hosts. His Lich Bloodline provided immunity to the death energy the parasite was generating in its death throes. His Perfect World cultivation techniques allowed him to work at the level of spiritual essence rather than merely physical biology.
Twenty minutes into the extraction, the first major fragment came free—a writhing mass of black energy that screamed with Muzan's hatred as Su Chen tore it from Kagaya's heart. The fragment immediately tried to escape, but Xiao Yi Xian's toxin barrier caught it. The moment the parasitic consciousness touched the rainbow film, it simply stopped existing—not destroyed through violence, but erased through conceptual negation.
"One fragment removed," Su Chen reported, his voice strained from the concentration required. "Approximately forty-seven more to go. Master Ubuyashiki, you're doing well. Your spiritual foundation is stronger than the parasite expected—it's having difficulty regenerating faster than I can extract."
Kagaya couldn't respond—he was too busy screaming through gritted teeth, his hands clutching the floor so hard that his fingers left indentations in the blessed wood. Amane, who had insisted on remaining in the room despite warnings about the process's brutality, held her husband's hand with tears streaming down her face.
The extraction continued. Fragment by fragment, Su Chen tore the parasitic consciousness from Kagaya's spiritual foundation. Some fragments came easily, their connections weak from centuries of stable existence. Others fought viciously, generating death energy and psychic attacks that would have killed normal practitioners.
But Su Chen was far from normal. He absorbed the death energy through his Lich Bloodline, neutralized the psychic attacks with Tatsumaki's copied sovereign-level mental defenses, and simply overpowered any physical resistance through his Formation Arrangement Realm cultivation base.
Two hours in, Shinobu spoke with clinical fascination despite the horror she was witnessing. "His technique is... it's beautiful in a terrible way. Every movement is precise. He's not just removing the parasite—he's simultaneously repairing the damage it caused. Look at how the golden energy fills in gaps where roots were removed. Master's spiritual foundation is actually becoming stronger than before infection."
"He's treating this like surgery," Gyomei observed, his spiritual perception tracking every detail. "But surgery performed at the level of the soul itself. I've never imagined such precise control was possible."
Three hours in, Kagaya lost consciousness—the cumulative pain finally exceeding what even his exceptional willpower could endure. Su Chen immediately adjusted his approach, working faster now that he didn't need to worry about the patient experiencing the process. The extraction accelerated, fragments being ripped free in rapid succession as divine energy flooded Kagaya's system.
Three hours and forty minutes in, Su Chen extracted the final and largest fragment—the main node that had served as the parasitic consciousness's core. It was massive, nearly the size of Su Chen's fist, pulsing with Muzan's concentrated hatred and rage at being discovered and excised.
The fragment tried one final desperate escape attempt, generating a burst of power that would have killed everyone in the room through spiritual shock. But Su Chen had anticipated this. He closed his hand around the fragment and simply crushed it, his Formation Arrangement Realm power overwhelming the parasite's final resistance. The fragment dissolved into black smoke that dissipated against Xiao Yi Xian's barrier before being absorbed and neutralized.
"Extraction complete," Su Chen announced, his voice showing the strain of four hours of intense spiritual work. "Master Ubuyashiki, the curse is gone. Your spiritual foundation is purified and repaired. You'll need approximately six months to fully recover, but you will recover. The curse that has plagued your family for generations ends with you."
He removed his hands from Kagaya's chest, and the golden light faded. The dark veins that had marked the curse's presence were gone—Kagaya's skin showed only healthy coloration, marred only by the scars and marks of previous symptoms. More importantly, his breathing had strengthened, his spiritual pressure had stabilized, and his overall life force radiated with vitality that had been absent before.
Amane immediately moved to her husband's side, checking his pulse and breathing with the expertise of someone who had nursed a dying man for years. Her expression transformed from desperate hope to overwhelming relief as she confirmed what her senses told her.
"He's... he's actually recovering," she whispered, her voice breaking with emotion. "I can feel his heartbeat getting stronger. His breathing is easier. Su Chen-san, you actually did it. You saved him."
"I told you I would," Su Chen replied simply. He stood, swaying slightly from exhaustion—even his prodigious energy reserves had been depleted by four hours of intensive spiritual surgery. "Now, I suggest we let him rest. When he wakes, he'll be weak but fundamentally healthy. Feed him nutrient-rich foods, keep him hydrated, and don't allow any strenuous activity for at least a month. His body needs time to adjust to being curse-free after a lifetime of parasitic infestation."
Gyomei approached, placing one massive hand on Su Chen's shoulder in a gesture of profound respect. "You have saved our master's life and freed him from a curse we had all accepted as inevitable. The Demon Slayer Corps owes you a debt beyond measurement. Whatever you ask of us during this trial period, we will provide."
"I ask only what we already agreed upon," Su Chen replied. "Access to your archives, assistance hunting demons to test my team's capabilities, and honest evaluation at the end of the week. If you're satisfied with our performance, we proceed to full collaboration. If not, we part peacefully with no hard feelings."
Sanemi, who had observed the entire process with gradually decreasing suspicion, spoke up. "I was wrong to doubt you. That was... I've never seen anything like that. You really do possess power beyond our world's normal limits. And you used it to save Master rather than dominate us. That's not what an enemy would do."
"Recognition of that fact is sufficient thanks," Su Chen said. "Now, I need approximately two hours of rest to recover my energy reserves, then we can begin demon hunting operations. Shinobu-san, I presume your Crow network has intelligence on demon activity in the region?"
Shinobu nodded, her earlier skepticism completely replaced by fascination and the beginning of genuine respect. "We have reports of demon attacks in three separate locations. One appears to be a minor demon—suitable for new Demon Slayers as training. One is moderate threat level—a demon that has killed dozens. The third is serious—possibly an Upper or Lower Moon rank demon based on the severity of the attacks."
"We'll handle all three simultaneously," Su Chen decided. "Saeko and Esdeath can eliminate the minor and moderate threats as training exercises. I'll personally address the potential Moon-rank demon. By morning, this region will be significantly safer, and you'll have concrete evidence of what my organization can accomplish."
He turned toward the door, then paused. "Oh, and one more thing. The extraction generated significant amounts of death energy and parasitic fragments. Some might have survived despite the barriers. I recommend having someone thoroughly purify this room before Master Ubuyashiki returns to it. Xiao Yi Xian can provide a cleansing compound that will eliminate any residual contamination."
"I'll handle it personally," Shinobu volunteered immediately. "And I would like to discuss the toxin barrier technique you demonstrated, if you have time later. The conceptual poison approach could revolutionize how we fight demons."
"That's exactly the kind of collaboration I was hoping for," Su Chen replied with satisfaction. "Rest for two hours, then we hunt. Let's show the Demon Slayer Corps what they've been missing."
Esdeath released her time dilation field, and causality snapped back to normal flow. From the perspective of those outside the ceremony room, only thirty minutes had passed—but those who had witnessed the extraction knew that four hours of intensive work had saved their master's life.
Word spread through the estate within minutes. The Hashira who hadn't been present for the extraction arrived demanding details. The lower-ranked Demon Slayers whispered in awe about the mysterious visitors who possessed power beyond anything their world produced naturally. And in the ceremony room, Kagaya Ubuyashiki slept peacefully for the first time in decades, his body finally free to heal now that the curse consuming it had been utterly destroyed.
Su Chen retired to a guest room, sitting in meditation to restore his depleted reserves. The curse extraction had been necessary—both to prove his capabilities and to establish goodwill with the Corps. But it had also been genuinely satisfying in a way he hadn't anticipated. Saving Kagaya's life served his strategic objectives, yes, but there had also been simple satisfaction in solving a problem that had tormented this family for generations.
Perhaps he was becoming more than just a ruthless power-seeker. Or perhaps he was simply learning that strategic pragmatism and genuine compassion weren't mutually exclusive. Either way, the first step of his Demon Slayer world operation had succeeded beyond expectation.
Now came the second step: demonstrating combat superiority by eliminating demons with such overwhelming efficiency that the Hashira would have to acknowledge his organization's value.
Three demons would die tonight. And if one of them was indeed a Moon-rank demon, Su Chen would get his first chance to copy the unique Blood Demon Arts that made Muzan's elite servants so dangerous.
The harvest was beginning in earnest. And by the time it concluded, the Demon Slayer world would have contributed everything of value it possessed to Su Chen's ever-growing collection of powers and capabilities.
Two hours until the hunt began. Su Chen closed his eyes, cycling his energy through practiced patterns, preparing for the night's work.
The demons of this world were about to learn that there were far worse things in the multiverse than Muzan Kibutsuji.
And one of those things had just arrived in their dimension.