The dimensional rift in the ruins of Kyoto pulsed with unstable energy, its edges flickering between reality and void like a wound in space that refused to heal properly. Su Chen stood before it with his selected team, analyzing the rift's structure with his dual pupils. The golden eye revealed energy flows connecting this reality to the Demon Slayer dimension, while the silver eye showed him the spatial framework that made transit possible.
"Stability assessment: sixty-three percent," Su Chen announced after completing his analysis. "The rift is degrading slowly—we have approximately two weeks before it collapses entirely or becomes too unstable for safe passage. That's our operational time window."
Saeko adjusted her blade's positioning, her Supreme Sword Bone already resonating with anticipation. She had spent the past twenty-four hours reviewing Su Chen's logs from his previous Demon Slayer visit, studying the breathing techniques and combat styles he'd documented. "Two weeks to acquire all breathing styles, copy relevant demon abilities, and recruit suitable individuals. Ambitious but achievable if we work efficiently."
Esdeath's expression showed unusual focus—she had been particularly interested in the Demon Slayer world's premise once Su Chen explained it. A dimension where humans fought demons through pure skill and technique rather than overwhelming supernatural power appealed to her sense of martial excellence. "What's our entry strategy? Announce ourselves to the Demon Slayer Corps immediately, or conduct independent operations first?"
"Immediate contact with the Corps," Su Chen decided. "Nezuko's presence provides instant credibility. We'll arrive at the Ubuyashiki estate—the Corps headquarters—and offer direct support in eliminating the demon threat. In exchange, we gain access to their complete archives, training facilities, and opportunities to recruit talented individuals."
Xiao Yi Xian spoke quietly, her silver form shimmering slightly with barely contained toxins. "You mentioned an Insect Hashira who specializes in poison. I'm... curious to meet someone who has refined toxin-based combat without possessing a Poison Body. Her techniques might provide insights I haven't considered."
"Shinobu Kocho," Su Chen confirmed. "She'll be fascinated by you as well—your existence proves concepts she's theorized about for years. The interaction should be mutually beneficial." He turned his attention to Nezuko, who stood beside him wearing traveling clothes rather than her usual demon attire. "Ready to go home?"
The demon girl nodded enthusiastically, making excited humming sounds. She had been looking forward to this since learning about the rift—she missed Tanjiro and wanted to show him how much she'd grown during her time with Su Chen's organization.
"Then let's proceed," Su Chen stated. He activated a protective formation around the team—unnecessary for himself at Formation Arrangement Realm, but useful for ensuring no one got separated during transit. "Dimensional crossing in three... two... one."
They stepped through the rift, and reality inverted.
The transition was more violent than Su Chen's previous dimensional travels—natural rifts lacked the refined stability of purposefully opened gates. Colors became sounds became textures became concepts, all mixing together in chaotic sensory overload that would have driven unprepared travelers insane. But Su Chen's team had experience with dimensional transit, and they maintained mental coherence through the disorientation.
Reality reasserted itself, and they emerged into early evening in a bamboo forest. The air smelled different from Earth—cleaner, less saturated with spiritual energy, carrying the distinctive quality of a world where cultivation wasn't the dominant power paradigm. Su Chen immediately activated his enhanced perception, scanning the area for threats or observers.
"No immediate contacts detected," he reported. "We're approximately forty kilometers from what I recognize as the Ubuyashiki estate based on geographical reference points. Local time appears to be early Taisho period, roughly 1912-1915 by Earth's calendar. Cross-referencing with my previous visit suggests approximately three years have passed in this dimension."
"Three years," Saeko calculated quickly. "So Tanjiro has had time to train and develop. The main timeline events might already be progressing."
"That's actually ideal," Su Chen replied. "If we arrived too early, the Corps would be scattered with no central coordination. Too late, and Muzan might already be defeated or in hiding. Three years suggests we're hitting the timeline around when the Hashira are assembled and active operations against Upper Moons are underway."
Nezuko suddenly made an urgent sound, her demonic senses detecting something her human companions hadn't yet noticed. She pointed toward the north, her expression showing excitement rather than alarm.
Su Chen extended his perception in that direction and caught a familiar spiritual signature. "Tanjiro. He's approximately two kilometers away, moving toward us at speed. His spiritual pressure suggests he's progressed significantly—I'd estimate him at roughly Engravement Realm equivalent now, much stronger than during my previous visit."
"Should we meet him en route or wait here?" Esdeath asked.
"Wait here," Su Chen decided. "Let him come to us. Nezuko's presence will announce our identity before any potential misunderstandings occur."
They settled into casual waiting positions, though each member maintained combat readiness out of professional habit. The forest around them was peaceful—birds singing, wind rustling through bamboo, the sun beginning to set and paint the sky in shades of orange and red. It was almost idyllic compared to the apocalyptic wastelands of Earth or the divine-energy-saturated danger zones of the Perfect World.
Footsteps approached rapidly, and Tanjiro burst through the bamboo grove with his hand on his blade's hilt. He had grown since Su Chen's previous visit—taller, more muscular, his movements carrying the confidence of someone who had survived countless battles. His eyes widened in recognition when he saw the group, particularly focusing on Nezuko.
"Nezuko!" Tanjiro's voice carried overwhelming relief and joy. He rushed forward, then stopped abruptly as he processed her appearance. She wasn't in her usual small form, wasn't wearing the bamboo muzzle—she stood normally, dressed like a human, clearly in complete control of herself. "You're... you're okay? You look so different!"
Nezuko hummed happily and ran to embrace her brother. They held each other for a long moment while Tanjiro struggled to process what he was seeing. When they finally separated, he turned his attention to Su Chen, his expression showing a complex mix of gratitude, confusion, and cautious wariness.
"Su Chen-san," Tanjiro greeted formally, bowing respectfully. "You returned. And you've been taking care of Nezuko all this time? She looks healthy, she's not... she hasn't hurt anyone, has she?"
"She's been perfectly safe and well-behaved," Su Chen assured him. "I've been feeding her concentrated spiritual energy instead of human blood or flesh. She's actually grown stronger through proper nutrition—her demonic abilities have developed considerably. She can now speak in short phrases, control her transformation more precisely, and has gained several new abilities."
"Speaking?" Tanjiro's eyes widened further. "Nezuko, can you really...?"
"Onii-chan," Nezuko said carefully, her voice slightly rough from disuse but clearly intelligible. "Missed you."
Tanjiro's eyes immediately filled with tears, his emotional nature overwhelmed by hearing his sister speak for the first time since her transformation. "Nezuko... you can talk. You're becoming human again!"
"Not quite," Su Chen corrected gently. "She's becoming something different—still a demon, but one who has transcended the normal limitations of her species. She's evolving into a new category of existence. Similar to what I'm attempting with my own development, actually."
Tanjiro wiped his eyes and composed himself, his natural earnestness reasserting itself. "I'm grateful beyond words for everything you've done for Nezuko. But I have to ask—why did you return? And who are your companions?"
"Introductions first," Su Chen gestured toward his team. "This is Saeko Busujima, a master swordswoman. Esdeath, a warrior specializing in ice-based techniques. And Xiao Yi Xian, a poison expert. They're members of my organization, the Stellar Void Pavilion."
Each woman nodded acknowledgment as they were introduced. Tanjiro's enhanced sense of smell—his supernatural ability to detect emotions and intentions through scent—was working overtime as he analyzed the newcomers. His expression became increasingly bewildered.
"Your friends smell... wrong," Tanjiro said bluntly, his social grace overridden by confusion. "Not bad, but strange. Like they come from somewhere very far away. Somewhere that shouldn't exist. And their strength..." He focused on Su Chen specifically. "You've become incredibly powerful. Three years ago, you were strong, but now you feel like something that could destroy this entire forest with a gesture."
"Accurate assessment," Su Chen confirmed without false modesty. "I've advanced significantly since my last visit. Which brings me to why I returned: I'm here to complete what I started. During my previous visit, I acquired some breathing techniques and established friendly relations with you and Nezuko. But I didn't fully explore this world's potential. Now I have the time and resources to do so properly."
"Specifically," Su Chen continued, "I want to offer the Demon Slayer Corps a proposition: I will help you eliminate Muzan Kibutsuji and end the demon threat permanently. In exchange, I request access to your complete archives—all recorded breathing techniques—and the opportunity to recruit talented individuals who might be interested in joining my organization."
Tanjiro's expression became conflicted. "That's... that's an incredible offer. Muzan has been the Corps' enemy for over a thousand years. If you could really eliminate him..." He trailed off, clearly wanting to believe but uncertain. "But why would you help us? What do you gain from eliminating our world's demons?"
"Knowledge, techniques, and allies," Su Chen replied honestly. "Your breathing styles represent a unique approach to enhancing human capabilities that I haven't encountered in other dimensions. Your demon blood arts showcase biological adaptations worth studying. And your Corps contains individuals whose skills and determination would benefit my organization. I'm not offering charity—I'm proposing mutually beneficial exchange."
"Other dimensions?" Tanjiro's confusion deepened. "I don't understand. Are you saying you're not from our world originally?"
"Correct," Su Chen confirmed. "I'm a dimensional traveler—someone who can move between different realities. Your world is one of many I've visited in pursuit of power and knowledge. That might sound alarming, but consider: I've had access to Nezuko for three years. If I intended harm to your world, I could have caused it already. Instead, I've protected and nurtured your sister."
Tanjiro considered this carefully, his scent-based empathy trying to determine Su Chen's true intentions. After a long moment, he nodded slowly. "Your scent is complicated—you're driven by ambition and self-interest, but you're not cruel or deceptive. You believe what you're saying about mutually beneficial exchange. And Nezuko trusts you completely—I can smell her affection and loyalty. That's enough for me to at least bring your offer to Master Ubuyashiki."
"That's all I ask," Su Chen replied. "Introduce us to your Corps leadership, and let us demonstrate our capabilities. Once they see what we can offer, the decision becomes obvious."
"Master Ubuyashiki is..." Tanjiro paused, choosing his words carefully. "He's dying. A curse has afflicted his family for generations, and it's killing him slowly. The Corps is preparing for potential succession issues. If you could somehow help him..."
Su Chen's interest sharpened immediately. "A curse? Describe the symptoms and progression."
Tanjiro explained what he knew about the Ubuyashiki family curse—how each generation's head died young, how it seemed connected somehow to Muzan's existence, how no medical treatment had proven effective. Su Chen listened with growing understanding, his enhanced comprehension recognizing the curse's nature.
"That's not a curse in the mystical sense," Su Chen concluded. "It's a spiritual parasite—probably something Muzan created centuries ago to cripple the family leading the organization hunting him. The 'curse' is actually a fragment of Muzan's consciousness that has infected the Ubuyashiki bloodline, slowly consuming their life force."
"Can you cure it?" Tanjiro asked hopefully.
"Possibly," Su Chen replied. "I'd need to examine Ubuyashiki directly to confirm the diagnosis, but if I'm correct, I can extract the parasitic consciousness and seal the infection. That alone would be worth considerable goodwill from the Corps."
Tanjiro's expression brightened with hope. "Then please, come with me to the estate! Master Ubuyashiki should meet you as soon as possible!"
They followed Tanjiro through the forest, traveling at speeds that would have been impossible for normal humans. Even Tanjiro, who had trained extensively, struggled to keep pace with Su Chen's team—their casual jogging matched his full-speed sprint. They reached the Ubuyashiki estate just as night fell completely, the compound's lanterns creating pools of warm light against the darkness.
The estate was larger than Su Chen had expected—a sprawling complex of traditional buildings surrounded by carefully maintained gardens. Guards were positioned at strategic points, though their spiritual pressure suggested they were regular Corps members rather than Hashira. As Tanjiro led the group toward the main building, a figure emerged from the shadows.
She was small, almost childlike in stature, with long black hair and a distinctly insect-themed haori. Her expression was pleasant—a small, constant smile that seemed more habitual than genuine. But her eyes held depth that suggested significant life experience, and the spiritual pressure emanating from her marked her as Hashira-level.
"Ara ara, Kamado-kun," the woman said in a soft, almost sing-song voice. "You're bringing guests? Such unusual guests too. That tall woman gives off an interesting scent—does she perhaps specialize in poisons?"
"Kocho-san!" Tanjiro greeted her respectfully. "These are Su Chen-san and his companions. They've come with an important offer for Master Ubuyashiki. And yes, one of them is a poison specialist—her name is Xiao Yi Xian."
Shinobu Kocho's attention fixed on Xiao Yi Xian with laser focus, her pleasant smile becoming slightly more genuine. "A poison specialist? How delightful! I'm Shinobu Kocho, the Insect Hashira. I would love to discuss techniques with you sometime."
Xiao Yi Xian inclined her head politely. "I would enjoy that as well. Your reputation precedes you—Tanjiro has spoken of your skills."
Before the conversation could continue, another presence manifested—this one significantly more powerful than Shinobu's. A man materialized from the darkness with such perfect stealth that even Su Chen's enhanced perception had barely detected his approach. He was massive, easily over two meters tall with extensive scars and a stone Hashira marking.
"Unknown visitors," the man stated in a deep, rumbling voice. "Strong. Very strong. The tall blue-haired woman feels dangerous. The black-haired woman's sword intent is sharp enough to cut space. And the leader..." His blank, unseeing eyes—the man was blind—somehow focused precisely on Su Chen. "The leader has transcended normal limitations. Formation-level spiritual pressure in a world where such things shouldn't exist."
"Himejima-san," Tanjiro interjected quickly, "they're here to help! Su Chen-san offered to assist in eliminating Muzan!"
The blind stone Hashira—Gyomei Himejima—remained cautious but not hostile. "Bold claim. Also suspicious. Why would entities of such power concern themselves with our world's demon problem?"
"Because your breathing techniques and demon abilities are valuable," Su Chen replied honestly. "I collect knowledge and power from across dimensions. Your world offers unique capabilities worth acquiring. In exchange for access to your techniques and permission to recruit talented individuals, I'll solve your demon problem permanently."
More figures began appearing as other Hashira responded to the disturbance. A flamboyant man with flashy jewelry and three women trailing behind him. A woman with pink and green hair who radiated innocent enthusiasm. A scarred man with wild hair who immediately took aggressive stance. A quiet man with heterochromatic eyes who observed without speaking. A young-looking boy with an absent, dreamy expression.
The Hashira had assembled in response to unusual visitors, and Su Chen found himself the focus of nine of the most powerful warriors in this dimension—technically only eight present, as he noted one Hashira was apparently absent. The spiritual pressure in the courtyard intensified as each warrior subconsciously released their power in response to potential threat.
Su Chen smiled calmly, completely unbothered by the display. These were impressive warriors by this world's standards—equivalent to Engravement or Formation Arrangement Realm cultivators. But he had just survived the Heavenly Tomb and broken through to genuine Formation Arrangement Realm with divine energy baptism. The entire assembled Hashira together couldn't threaten him if they attacked simultaneously.
"Shall we discuss this with your Master?" Su Chen suggested pleasantly. "Or would you prefer a demonstration of capabilities first? I'm happy to prove my claims through whatever method your leadership prefers."
Before anyone could respond, a soft voice emerged from the main building. "Please, let us speak peacefully. Violence is unnecessary when words suffice."
A man emerged—or rather, was carried on a palanquin by attendants. He was clearly ill, his skin showing the mottled discoloration of advanced curse progression, his breathing labored, his body fragile. But his eyes were clear and kind, showing wisdom and compassion despite obvious suffering.
Kagaya Ubuyashiki, leader of the Demon Slayer Corps, had arrived. And the negotiation was about to begin.