Shinobu found Sasori near the village gate, where Kanao awaited her.

"Kanao? What are you doing here?" Shinobu inquired.

"Kenji said you needed me on a mission, Master," Kanao replied as a crow landed on Shinobu's shoulder.

"Kenji..." Shinobu muttered, eyeing the crow on her shoulder. "Don't attempt to lecture me. You should be taking your Tsuguko with you, not some random kid!" The crow, known as Kenji, spat.

"That 'kid' is older than all of us, plus he has a good track record," Shinobu retorted, beginning to leave.

"But since you're here, You can come with," Shinobu said sounding cheery. "Now let's find a ride." She said, starting to walk towards a couple of merchants.

"Why do we need a ride?" Sasori asked. "The mountain is about 70 miles away; it would take too long to get there by foot. And, we don't want to exhaust your old legs too much, old man," Kenji said in a snarky manner.

"What's wrong with your crow?" Sasori asked Kanao, but she did not say anything just looking on with a smile.

"Don't worry about Kenji, Sasori; he's like that with everyone," Shinobu explained. "Anyways, I got us a ride; we'll be leaving in 10 minutes." She said, guiding them towards a merchant.

"Mr. Hoshi, thank you for taking us," Shinobu said, smiling at a middle-aged man in his twenties.

"Don't mention it. I'm more than happy to help out any samurai," Mr. Hoshi replied graciously

"We just need to wait till my niece with her shopping." Mr. Hoshi said leaning on the Carriage

"Hey, Shinobu. How did you get a job as a doctor in that the degree from the core didn't count?" Sasori asked "Quite simple. I bought it." Shinobu replied making Sasori raise an eyebrow.

"You bought the clinic? Why?" Sasori asked, "It was convenient." Shinobu answered.

A girl wearing a blue kimono cane near them holding three bags "Hey Uncle! who are those people?" She asked.

"They are samurai requiring travel." Mr. Hoshi explained

Shinobu smiled warmly at the girl. "This is my niece, Misaki," Mr. Hoshi introduced.

Misaki's eyes widened as she saw Shinobu and the others. "Wow, are you all samurai?" she asked in awe.

Shinobu nodded, her smile gentle. "Yes, we are," she confirmed. "We're going on a mission to investigate some disturbances near Mount Natagumo."

"That sounds exciting!" Misaki exclaimed, her curiosity piqued.

"Pack everything up. We batter get going." Mr. Hoshi said gating on the Coach Box.

-Near Mount Natagumo-

The group finally arrived at their destination as the sun already set, casting darkness over the dense forest surrounding Mount Natagumo. The air was thick with tension, the ominous presence of the mountain looming over them.

They waved goodbye to Mr. Hoshi and Misaki as the carriage rolled away.

"Stay close, everyone," Shinobu instructed, her voice steady but cautious. "We need to be on high alert. We don't know what to expect." She started to move towards the mountain, but Sasori grabbed her by the back of her collar.

"What is it?" Shinobu asked.

Sasori walked to the front of the mountain and pulled what seemed to be a piece of string with one of his fingers. As he released it, the string snapped back into place, revealing an intricate web of threads surrounding the mountain that had been almost invisible in the fading light.

The barrier shimmered slightly, and the web-like structure reflected.

Shinobu's eyes widened as she watched Sasori's quick thinking and decisive actions. "My my, a protective barrier, one that covers the whole mountain. We must be dealing with a strong demon to create something like this," she mused, her voice tinged with admiration.

Kanao stepped forward, her gaze unwavering. "Should we find another way around?" she asked, her voice calm despite the situation.

Shinobu shook her head. "No, we need to confront this head-on. Kanao, while you please do the honors," she instructed.

Kanao nodded, unsheathing her sword and raising it high above her head. With a swift motion, she brought it down upon the barrier, but to everyone's surprise, the barrier was too strong to cut instead her sword was cut in half. The top part of the sword went flying to wards Sasoris head but he moved out of the way and the broken part was embedded in the ground.

"Never mind it seems as if we need to find another way," Shinobu said "Got any ideas Sasori?" She asked looking at him.

"Yep." Sasori said pulling out a scroll and a katana came out of it "Her you'll need a sword." He said offering it to Kanao.

Both of them looked at Sasori with confusion "How...How did you do that?" Shinobu asked, "I don't want to waste time on explaining." Sasori said handing the katana to Kanao.

"Now I'm going to dig a hole under the barrier. You two need to go through as fast as you can before it closes up," Sasori instructed, performing several hand signs with swift precision.

"And how are you going to dig a ho—" Shinobu began, but her question was cut short as a hole appeared under the barrier.

"Now," Sasori said, ducking under the barrier. Shinobu and Kanao snapped out of their confusion and quickly followed him through the opening, just before it closed up behind them.

"How?" Shinobu asked, dumbfounded by the ease with which Sasori had bypassed the barrier.

"I don't want to waste time explaining. We've got a demon to kill, after all," Sasori replied tersely.

"Okay, fine, but first we need to find survivors," Shinobu said, as the sound of lightning echoed through the forest.

"We need to split up. Go find any survivors," Shinobu instructed, leaping toward the source of the lightning.

Kanao immediately dashed off, leaving Sasori alone. He pulled out a scroll, unrolling it to release a puppet—a bandit leader with a yellow neckerchief and a gun holster at his hips. The puppet moves in a different direction from where Sasori goes.

'Time to see if his eyes work,' Sasori thought, closing one of his eyes. Instead of darkness, he saw through the bandit leader's eyes. He gave a small smile, opening one eye to maintain dual visions. 'Not used to seeing two visions at once, It seems I just have to get used to it fast.'

As Sasori entered a clearing, he witnessed a giant spider-humanoid demon crushing the head of a child wearing a boar head. Without hesitation, Sasori lunged at the demon, slicing through the arm that was crushing the boy. As he landed, he swiftly cut the demon's legs, causing it to stumble. The demon attempted to catch itself with its remaining arm, leaving its neck exposed for Sasori to deliver a swift, fatal cut.

'Who is this guy? I've never seen anyone... as incredible as this guy! He sliced through that tough-as-nails monster like tofu! Amazing! Simply amazing!' Inosuke thought to himself, his eyes wide with awe as he looked at Sasori, who was already leaving the scene.

"Hold up a second! Crimson Clown! Fight me!" Inosuke shouted, trying to grab Sasori's attention.

Sasori stopped in his tracks, his eyes narrowing as he turned to face Inosuke. "Crimson Clown, huh? Interesting choice of words," he remarked, his voice calm and measured.

Inosuke, still brimming with adrenaline, brandished his swords. "You're not running away from me! I want to see what you're made of!"

Sasori's expression remained stoic as he regarded the boar-headed boy. "We don't have time for this. There are more demons to slay, and survivors to rescue."

Inosuke growled, frustration evident in his voice. "Coward! Face me!"

Sasori sighed, and then in a flash, he was right in front of Inosuke, his sword resting gently against Inosuke's throat. "We can spar later. For now, we focus on the mission." He lowered his sword, stepping back and turning away once more.

Inosuke's eyes widened in shock at Sasori's speed and precision. "Fine," he muttered, grudgingly sheathing his swords. "But don't think this is over, Crimson Clown!"

Sasori gave a slight nod. With that, he continued his path deeper into the forest.

-The bandit leader puppet-

Sasori used one of his hands to deftly control the puppet, which moved smoothly through the dense terrain. As the puppet advanced, it navigated under several trees, their branches adorned with large, cocoon-like structures that held human remains. The eerie sight did not deter Sasori; his focus was unwavering.

The puppet continued its path until the sound of distant screams drew its attention. It moved swiftly towards the source, soon arriving at a harrowing scene: The boy with Hanafuda earrings he had met on his first mission and his demonic sister were being held hostage by a short-stature demon. The captor's appearance was unsettling—milky white skin with red dots adorning his face, light pink hair resembling spider legs, and eyes that were a disturbing combination of red sclera and pale blue irises. The kanji for "Lower Three" was etched into his left eye, marking his rank among the demons.

Sasori maneuvered the puppet into position, aiming its gun at the Lower Rank Three demon. However, juggling two visions and controlling the puppet's firearm proved challenging. The first shot missed the demon's head, hitting his shoulder instead.

The puppet swiftly reloaded and unleashed a barrage of bullets, but Rui, the demon, used Nezuko as a shield, blocking most of the shots. His annoyance was palpable. "Who are you? You're neither human nor demon. You're like one of Mother's puppets, but she's dead. So who are you?" Rui demanded, his voice filled with irritation as he launched several slashes of his strings at the puppet.

The puppet evaded the attacks, jumping high into the sky and quickly reloading the revolver. As it descended, it aimed and fired again with remarkable precision. This time, the bullets found their mark, forcing Rui to release his grip on Nezuko.

Meanwhile, the boy with the Hanafuda earrings, Tanjiro, seized the opportunity. "Nezuko, are you okay?" he called out, rushing to her side as the puppet kept Rui occupied.

Rui, enraged, intensified his attacks, but the puppet's agility and Sasori's precise control kept it out of harm's way. "You're a nuisance!" Rui shouted, launching a powerful barrage of strings.

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Sasori made the puppet fire at Rui, hitting his shoulder again. Rui howled in frustration, but this distraction was all Tanjiro needed. He surged forward, his snaped katana attempting to cut Rui's neck but the katana didn't even press the neck of Rui.

Sasori was rushing in the direction of the fighting when a girl, whose physical features were very similar to Rui's, appeared from behind him, attempting to capture him in a silk cocoon. Her movements were swift and deadly, a testament to her demonic strength.

Sasori reacted immediately, rolling to the side to avoid the silk threads. "So there's more of you," he muttered, his eyes narrowing as he sized up his new opponent.

The girl sneered, her eyes glinting with malice. "Rui warned me about you. If I kill you, I'll still be his favorite." She launched another volley of silk threads, aiming to ensnare Sasori.

Sasori quickly countered, using his strings to manipulate the terrain around him. He caused branches and debris to intercept the silk threads, creating a makeshift barrier. "You underestimate me," he said, his voice calm and measured.

While the bandit leader puppet continued its assault on Rui, Sasori summoned another puppet from his arsenal. This one was smaller and more agile, equipped with sharp blades. He directed it to engage the girl, buying himself time to strategize.

The girl hissed in frustration as the blade-wielding puppet closed in on her, slashing at her with rapid, precise movements. She dodged and retaliated with her silk threads, but the puppet was relentless, its attacks forcing her to remain on the defensive.

Back at the main battle, Rui was growing more desperate. "Enough of this!" he roared, his strings becoming more erratic and dangerous. The puppet and Tanjiro coordinated their efforts, evading his attacks and searching for an opening.

Sasori saw his chance and aimed directly at Rui's neck, but suddenly a small tornado of silk began to swirl around Rui. When it cleared, Rui was nowhere in sight.

Tanjiro looked confusedly at the spot where Rui had been standing. "What just happened?" he muttered to himself, still catching his breath.

Rui was suddenly in his house. He looked around, his eyes landing on a demon. The demon's skin was unnaturally smooth and pale, giving him an almost spectral appearance. His hair was jet black and cascaded down to his waist in thick, glossy waves, often seen flowing gently as if caught in a perpetual breeze. His eyes were a striking crimson, glowing with an unsettling intensity.

"What brings you here, Kyoku?" Rui asked. "Don't you see I'm in the middle of some family matters?"

"Lord Muzan instructed me to tell you to get the red-headed slayer out of here unharmed," the demon, now known as Kyoku, said.

"Red-headed slayer? The one Lord Muzan told us not to engage? He's here?" Rui asked.

"Yes, he was the one controlling the puppet that was attacking you and killing your father," Kyoku informed him.

"He has powers similar to my mother's? He killed my father," Rui said, sounding like he was contemplating something.

"Rui, I know that look. Don't let your feelings interfere with our lord's orders," Kyoku said. "Lord Muzan wants him to be safe, right?" Rui asked. Kyoku nodded.

"Then he will be perfectly safe with me as a member of my family," Rui said, beginning to leave.

"Rui, don't disregard Lord Muzan's orders! Follow them!" Kyoku said, starting to get angry.

"He killed my father. It's only fair if he becomes my new father, and that other demon as my sister. I will have my family," Rui said, ignoring Kyoku.

"RUI, FOLLOW OUR LORD'S ORDERS—" Kyoku began to say, but he was cut off by Rui slicing him into several pieces with his strings, destroying a part of his house with the attack.

"Family... My family," Rui's voice wavered with emotion, a haunting refrain that echoed through the empty halls of his home.

Yet, as he felt the tendrils of darkness begin to coil around his very being, Rui knew that he could no longer ignore the truth that lay hidden within his own heart. With a surge of determination, he tore out his own eyes, a painful sacrifice in pursuit of newfound clarity and purpose.

As his eyes regenerated, now marked with the title "Former Lower 3," Rui's voice rang out with a newfound resolve. "Nothing... Nothing will come between me and my family," he declared, each word laced with determination as he leaped into the unknown, his path illuminated by the flickering flames of his own inner strength.

Sasori finished off the demon girl, and suddenly Aki appeared out of nowhere. "Sasori, go protect the demon girl," she said.

"Why? What's with you and this demon girl?" Sasori asked.

"Just do it!.. It is an order from the leader of the corps now!" Aki said, sounding panicked.

Sasori's eyes narrowed, and he began to travel to where the two siblings were.

Nezuko was trying to lift Tanjiro off the ground when they both suddenly saw butterflies. Nezuko saw a woman lunging at them, and she moved in front of Tanjiro to protect him. Suddenly, Giyu appeared in front of her and blocked the strike from Shinobu.

"Oh, my?" Shinobu said, landing gracefully on the ground. "What are you doing here, Tomioka? Are you following me? If you wanted to ask me out, all you had to do was ask~" Shinobu teased Giyu.

"They needed someone to bring the Kakushi here safely. Luckily, I was there to take them," Giyu said.

"You once told me men and demons could not be friends? How should I put this... This is exactly why nobody likes you, y'know?" Shinobu said, pointing her stinger-shaped katana at Giyu.

Giyu moved in front of the two siblings. "Now, now, Tomioka, please move out of the way," she said.

"I'm not... I'm not disliked by people," Giyu said.

"Ah, I apologize. You have yet to realize what people think of you, huh? That was uncalled for. Please forgive me," Shinobu said, apologizing. "Little boy," she asked.

"Yes?" Tanjiro replied.

"You're protecting a demon there. I don't want to hurt you, so please get out of the way," she said.

"Y-You're mistaken! Well, you're not, but... She's my little sister! So... you see..." Tanjiro explained.

"Is that right? Poor thing," Shinobu said, looking sad. "In that case, I shall use a gentle toxin to kill her, so she won't suffer, alright?" she said, smiling.

"Can you two move? Both of you need to make a run for it now," Giyu said.

"Tomioka... Sorry for the trouble!" Tanjiro said as he and Nezuko began to run off.

"Isn't that against the Demon Slayer Corps' rules?" Shinobu asked.

Tanjiro and Nezuko were running, and Tanjiro found his box bag and put it on. Both of them did not notice the presence atop the tree.

Tanjiro noticed Kanao coming at them, swinging her sword at Nezuko, but Tanjiro blocked the attack with his broken sword. "Run!" Tanjiro said to Nezuko, but she stopped running and looked at Tanjiro with concern.

"I'll be fine, just run!" Tanjiro said, but Kanao knocked him out with a neck chop. She immediately chased Nezuko, who changed her size to dodge her attackers.

Kanao was becoming annoyed but did not show it when rocks suddenly fell from the sky. Kanao grabbed or dodged the rocks, which were dropped by Aki.

Kanao used her sword to hit one of the rocks back at Aki, but she dodged it. When she looked back at Nezuko, she was a bit ahead of her, but she quickly caught up with her. When she began to swing her sword, she was suddenly lifted into the air.

When she looked up, she narrowed her eyes, seeing Sasori holding Nezuko by the back of her collar. A very large man stood next to him, his chest opened as he threw Nezuko inside the puppet and closed its chest, trapping Nezuko inside.

"My apologies, but currently we aren't on the same side, so I will be taking my sword back," Sasori said, using his strings to take the sword back from her.

For once, Kanao's expression changed, showing a look of dumbfounded surprise.

Shinobu came into the field, seeing Sasori take Kanao's sword from her with his mind. She couldn't help but feel concerned about what Sasori had said.

"Sasori, what are you doing?" she asked, Giyu quickly coming up behind her and seeing the redhead atop a tree.

"Ah, hahaha! Do not fear, for I am here!" Inosuke said, jumping out of a bush.

"My, my, Sasori, are you on their side?" Shinobu asked, her tone curious but cautious.

Sasori glanced at Inosuke, then back at Shinobu. "It's complicated," he said, his voice steady. "But for now, protecting this demon girl is my priority."

"I don't know why you are doing this, but in that case, we will have to fight," Shinobu said, her voice firm.

Sasori's eyes narrowed as he prepared his puppets for combat. "If you insist," he replied, his tone cold.

Before the tension could escalate further, a chilling presence washed over them. From the shadows, Rui emerged, his eyes now bearing the inscription "Former Lower 3."

"You won't take my family from me," Rui said, his voice cold and determined.

Giyu's eyes narrowed as he assessed the situation. "We need to regroup and figure out what's happening. This isn't normal," he said, stepping protectively in front of Tanjiro.

"Agreed," Shinobu said, her playful demeanor vanishing. "Let's get the children to safety first."

As they prepared to move, Rui's strings began to shimmer, creating a deadly barrier around him. "You can't escape," Rui hissed, his gaze locked onto Sasori. "I won't let anyone ruin my family."

Sasori stepped forward, his puppets at the ready. "Then we have no choice but to fight," he said, his voice resolute.

Inosuke, sensing the tension, readied his swords, his excitement palpable. "Finally, a real fight!" he exclaimed.

Tanjiro, though weakened, managed to stand. "We can't let Rui harm anyone else," he said, determination burning in his eyes.

Giyu and Shinobu exchanged a glance, both understanding the gravity of the situation. They couldn't afford to hold back.

"Let's do this," Giyu said, drawing his sword.

Shinobu nodded, her grip tightening on her katana. "For the sake of those we protect."

Two other puppets flanked Sasori: the Ren and bandit leader puppets, along with the large puppet containing Nezuko.

"Father, drop your puppets and join my family," Rui said, opening his arms as if inviting Sasori for a hug.

"Trust me, child, I'm not your father," Sasori said, using the bandit leader puppet to fire a bullet at Rui, who cut the bullet in half with his strings.

"How disappointing. It seems I just have to force you," Rui said, launching several strings at Sasori, who dodged them with ease.

"Don't you think it's time we tag team, Tomiyoka?" Shinobu asked. "We still haven't tested this yet. It may be a bad idea," Giyu replied, blocking several strings.

"Not the time to cover, Tomiyoka~" Shinobu teased, successfully goading him. "Fine," Giyu nodded, and they began their coordinated attack.

"Synergy Breathing: Liquid Venom!" Both Giyu and Shinobu declared.

A serene aura enveloped Giyu as he stood still, his presence calming and unyielding. The air around him grew heavy with moisture, and the ground beneath his feet seemed to ripple like water. In an instant, Giyu moved with blinding speed, his sword slicing through Rui's threads effortlessly. The water-like energy from his blade expanded, creating a wide arc that cut through the air, neutralizing Rui's initial assault and leaving him momentarily exposed.

With Giyu's attack creating an opening, Shinobu darted in, her movements swift and graceful. Her katana, laced with a potent wisteria-based poison, glowed with a soft purple light. She struck with rapid, precise movements, each attack targeting Rui's vital points in a hexagonal pattern. Her strikes were too fast for Rui to counter, and each one delivered a dose of poison that began to weaken him, even though his demonic physiology fought against it.

The combination of Giyu's overwhelming force and Shinobu's pinpoint precision and poison created a devastating tag-team attack. Rui, caught off guard by the seamless coordination, struggled to defend himself against the dual onslaught.

As Giyu's water techniques disrupted Rui's defenses, Shinobu's poison started to take effect, slowing his movements and dulling his reflexes. The synergy between their techniques created a perfect balance of offense and defense, making it nearly impossible for Rui to mount a counterattack.

Rui's face twisted in pain and fury. "You...you think this will stop me?" he spat, his voice strained as the poison began to sap his strength.

Giyu and Shinobu did not relent. "This ends now," Giyu said, his voice as calm and cold as a winter river.

Shinobu nodded, her eyes focused and determined. "For those we protect, and for those you've harmed," she added, her voice unwavering.

Together, they launched their final assault. Giyu's water-based attacks flowed seamlessly with Shinobu's poison-infused strikes, each movement perfectly timed and executed. The battlefield became a whirlwind of water and venom, each strike pushing Rui further into a corner.

But Rui didn't falter, using his strings to grab Kanao and Inosuke and throw them at Giyu and Shinobu.

Giyu managed to grab Inosuke and landed gracefully on the ground, but unfortunately, Shinobu was hit by Kanao, and they were both thrown into a tree, disrupting their attack.

Sasori sent Ren at Rui, his two blades crackling with lightning, attempting to strike him. But Rui jumped into the sky, using his strings to tie Ren's swords together and land on Ren's shoulders, pulling Ren's swords tightly so Sasori couldn't use them to attack.

Yet, amidst the chaos of battle, there was a plea, a cry from the heart of a child yearning for connection.

"Father, enough of this madness! Join me, join our family!" Rui's voice trembled with desperation, the echoes of his plea lost in the clash of steel and lightning.

Sasori's gaze softened for a fleeting moment, a flicker of sorrow passing through his eyes as he continued his assault. The weight of his decision hung heavy in the air, a silent testament to the conflict raging within his soul.

Sasori's movements were cold and calculated, his strings dancing through the air with lethal precision. With a flick of his wrist, he pulled Rui down, his sword finding its mark with chilling accuracy.

The young demon cried out in agony as Sasori's blade pierced his flesh, Ren's puppet body mirroring the brutal assault from behind. Lightning crackled and danced across Rui's form, each jolt sending waves of searing pain through his body.

The large puppet shifted its massive blade and brought it down onto Rui's neck, but Rui opened his mouth and released strings that severed the large puppet's arms. The sound of the large sword dropping to the ground was heard.

Yet, Sasori remained undeterred, his resolve unyielding as he orchestrated the final act of this tragic dance. With a swift motion, he dislodged his sword from Rui's chest, casting the young demon aside like a discarded puppet.

Ren's lifeless form moved at Sasori's command, his swords wrapping around Rui's neck with chilling precision. Rui's breath caught in his throat as the cold steel bit into his skin, his strings struggling against the relentless grip of his father's creation.

"Father, please..." Rui's voice was a desperate plea, his eyes pleading for a reprieve from the merciless onslaught. But Sasori's heart remained shrouded in shadow, his gaze betraying no hint of mercy.

With a heavy heart, Sasori raised his sword high, its gleaming edge poised to deliver the final blow. The moonlight bathed the scene in an eerie glow, casting long shadows upon the battlefield as father stood poised to strike down son.

Yet, Sasori's resolve remained unyielding. With a single stroke, he brought his blade down upon Rui's neck, the sound of metal meeting flesh drowning out the echoes of their shared agony. In that moment, as life faded from Rui's eyes, the bond between father and son was severed, leaving only the bitter sting of regret in its wake.