The air inside the Infinity Castle was thick with the scent of old wood and something sickly sweet—like overripe fruit left to decay. The shifting walls groaned as they rearranged themselves, twisting corridors into dead ends and staircases into yawning voids. Shinobu moved with careful precision, her steps as light as a butterfly’s wings against the polished floors, her breathing controlled.
And then she felt it.
The scent of blood.
It was revolting. She had been surrounded by blood for what felt like her entire life. Saving lives was a dirty business, and more often than not, she was forced to endure the sticky warmth of it on her hands, the metallic tang that clung to the back of her throat for days. But this—this was different. This was the stench that lingered in the ruins of villages razed by demons, where blood pooled in the streets, bodies left to decay under the unforgiving sun, limbs twisted at unnatural angles, terror forever etched into unseeing faces.
A familiar chill crept into her bones, laced with the faintest trace of iron and wisteria, as if the universe itself had frozen in anticipation. Her grip on her sword tightened.
She turned the corner—and saw him.
A demon. Blood stains at the top of his head, a carefree smile on his lips, and kanji etched into his rainbow-colored eyes.
Upper Moon Two.
"Ah! You’re here! A girl. You look young and delicious—I’ll have to thank Nakime later," he said, his voice gentle, almost warm. Yet her blood was boiling.
He sat languidly on a wooden platform, legs crossed, one hand resting against the mauled body of a young woman. His other hand idly held his black crown, removing it as if in some twisted gesture of respect. A serene smile curled his lips, but his eyes—those empty, glassy things—gleamed with something unreadable. He exhaled softly, as though delighted by the sight of her.
"Well, how are you? Nice to meet you. My name is Douma. It's a lovely evening, isn't it?"
Douma.
Shinobu didn’t move. Her blood roared in her ears, her body thrumming with tightly coiled restraint.
This was the demon who had stolen her sister, who had left her to die slowly in her arms, her warmth slipping away with every agonizing second. That moment had never left her. It clung to her like a shadow, whispering to her in the quiet hours of the night, in the spaces between heartbeats.
And now, after years of smiling through her hatred, after training until her body ached and her lungs burned—
She was finally here.
In between the discarded mangled bodies that littered the floor, one girl moved towards her. Her eyes were full of fear and desperation, her pupils shrinking and tears streaming down her face. Her hands moved through the wooden platform painstakingly slowly, covered in blood all the way to her elbows, maybe her own blood, maybe the dead friends that surrounded her.
Shinobu’s grip on her sword tightened as the girl’s voice broke through the heavy silence.
"He—help me…”
It was weak, barely a whisper, but unmistakably filled with pain. Shinobu’s eyes flickered toward the young woman, her body barely intact, clawing at the blood-slicked floor, trying to reach her.
"Shh! We are speaking,” he chided gently, tilting his head as if scolding a child.
Shinobu did not stop to think, she leaped into the platform, took the woman in her arms and jumped to the next platform in less than a blink. Putting some distance between the hurt woman and the demon.
“Are you okay?” She asked, she knew the answer to the question but at least it gave her some semblance of agency back, something else to think about.
"Woah! You are fast. Are you a Hashira?" he asked, blinking at her with something almost resembling curiosity.
She didn’t answer. Her lips pressed into a thin line.
But before Shinobu could take her to safety, Douma sighed and raised a finger to his lips. Then, with a flick of his wrist, his fan slashed through the air in a gleaming arc.
A sickening, wet sound followed.
The girl stilled instantly. Her breath caught, her fingers twitched once—then nothing. Blood splattered across the cold floor, a crimson offering to the demon who stood over them, expression never wavering from his placid, empty smile.
Shinobu’s nails bit into her palm.
"Don’t worry about her," Douma waved a dismissive hand. "Just leave her there, somewhere. I’ll make sure to devour her later.” His tone was light, conversational, as if they were simply two strangers exchanging pleasantries on a quiet evening rather than standing in the middle of a massacre.
Shinobu didn’t spare him a response. Instead, her gaze flicked toward the girl’s lifeless body. Her stomach twisted, but she forced herself to stay quiet.
Yes, her sister had talked about it. His weapon of choice was a pair of sharp golden fans, she had to figure out how to avoid them and what exactly he did with them.
"I am the founder of the Cult of Eternal Paradise” he said, beaming with something akin to pride. “My job is to make everyone who worships me happy—and that includes me. So I will devour her and leave no leftovers.”
Shinobu felt something dark curl in her chest. "Make everyone happy?" Her voice was deceptively soft, laced with something venomous. "Don’t be ridiculous. That girl was only asking for help."
Douma’s smile widened. "And that’s exactly why I rescued her. She feels no pain anymore, she’s not suffering, she has nothing to fear."
His words were spoken with such casual sincerity that, for a single horrifying moment, Shinobu almost believed that he believed them.
He twirled a fan between his fingers. "You know, everyone is scared of dying. That’s why I eat them—so they can live forever in me.”
His voice was light, almost wistful.
"All the feelings of my worshipers, their blood, their skin—I make sure to accept them, to rescue them, and guide them to spiritual enlightenment."
Something inside Shinobu snapped. Her grip on her sword was steady, but her body burned with the weight of her hatred.
She had spent years hiding her rage behind a smile, suppressing it beneath honeyed words and feigned amusement. But standing here, before the monster who had taken everything from her, she felt it pulse through her like fire in her veins.
The cold air inside Douma’s temple was cloyingly sweet—like flowers left to rot in stagnant water. The shifting walls groaned again, their endless movement an eerie reminder that this place was alive, pulsing and shifting with Muzan’s will.
Shinobu’s stomach twisted, rotting flowers, like her sister had been left to rot.
Her lips curled in disgust, bile burning at the back of her throat. “There’s no way you’re sane. Are you crazy? You’re making me want to vomit.” Her voice came out sharp, each syllable vibrating with the sheer force of her hatred.
Douma blinked, feigning surprise, before letting out a soft, airy chuckle. His delicate fingers lifted his fan, covering the lower half of his face as though he were amused rather than offended. The gesture was effortless, almost graceful—too graceful for the monster that lurked beneath.
“Eh? How can you be so rude when we just met?” he mused, tilting his head. His multicolored eyes shimmered under the dim light, their glassy depths reflecting nothing—no remorse, no understanding, no soul. Only a hollow, unsettling amusement. He let out a dramatic sigh, tapping his fan lightly against his chin. “Oh! I know! How sad. If I did something to upset you, I will make sure to listen, so just say it.”
Shinobu’s fingers curled tightly into the fabric of her haori, the soft weave pressing against her palm. Her breath was shallow, tight in her chest, like a vice closing in around her ribs. The hatred inside her coiled, sharp and suffocating, pressing against her lungs, her heart.
“Something to upset me?!” Her voice wavered—not with hesitation, but with the sheer force of her emotions straining against her self-control. The edges of her vision blurred for a moment, not from tears, but from the raw, searing rage that made her hands tremble. She lifted the hem of her haori, fingers tightening around the fabric, as if daring him to recognize it. “You killed my sister, didn’t you? Don’t you recognize this haori?”
For a moment, Douma simply stared at the garment. The silence stretched, long enough for Shinobu’s heart to pound against her ribs. Then, slowly, his lips parted in an exaggerated ‘ah!’ of remembrance.
“Oh! You mean that girl who used Flower Breathing?” He tapped a finger against his chin, tilting his head as though recalling a fond memory. His lips curled into a grin—serene, empty, utterly infuriating.
“She was a sweet and tender girl,” he said, sighing wistfully. “Such a shame, really. I missed the opportunity to eat her because the sun was about to rise.” His voice was light, almost playful, as though discussing an unfinished meal rather than a life stolen. His fan clicked shut, his fingers drumming lightly against the golden polished metal.
“Yes, I remember her.” His grin widened, revealing a flash of sharp teeth. “I really wanted to gobble her up.”
The moment the words left Douma’s lips, the world around Shinobu seemed to snap.
Something hot and violent surged through her veins, poisonous rage clawing up her throat, threatening to choke her. Her fingers tightened around the hilt of her sword, her knuckles whitening. The gentle, practiced smiles she had worn for years shattered like fragile glass, leaving behind nothing but raw, unfiltered fury.
Douma barely had time to register the shift before she lunged.
In a blur of movement, she shot forward, her speed a streak of violet against the dim glow of the Infinity Castle. Her blade gleamed, catching the flickering candlelight as it sliced through the air, aimed straight for his smug, empty face.
Douma’s instincts kicked in—he moved to block her, his hand lifting in an effortless motion, fingers splaying out to catch the blade before it could reach him.
But he had underestimated her rage.
Her Nichirin sword didn’t stop.
The tip of the blade pierced through the narrow gap between his fingers, slicing through flesh and bone as if they were paper. A sharp, wet crunch filled the air as the steel forced its way through, slipping past his outstretched hand—unstoppable, unrelenting—until it plunged straight into his eye.
A sickening squelch. A burst of black, inky blood.
Douma’s head snapped back.
For the first time, his grin faltered, his face twisting in surprise. A strangled laugh bubbled up in his throat, more amusement than pain, though his fingers twitched around the edge of her blade.
“Oh my, that was a good stab,” he murmured, his voice thick with something unreadable. His blood dripped in sluggish rivulets from his eye socket, splattering onto his pale skin like dark ink staining porcelain. “I couldn't stop it with my hand .”
Douma let out a breathy chuckle, his expression caught somewhere between delight and admiration, but the amusement in his eyes flickered as he shifted into an attack.
“Blood Demon Art: Frozen Lotus.”
Shinobu’s heart pounded against her ribs, the air around her turned so cold it could have destroyed her lungs, but she refused to let up. Her arms burned with the force of her strike, the raw fury behind it making her breath come out in ragged bursts, her own breath formed thick clouds before her.
A bitter chill exploded outward. The air around Shinobu turned razor-sharp, an unnatural frost creeping along the ground, crackling against the walls of the Infinity Castle. The sudden drop in temperature stabbed at her lungs, each breath a sharp, stinging ache that burned from the inside out.
But she refused to let up.
Her arms trembled with exertion, every muscle alight with the force of her strike. As Douma’s attack surged toward her, she moved instinctively, dodging at the last second. She arched backward, her body bending with practiced precision, her weight shifting into her hands and then back to her feet—one of Mitsuri’s exercises ingrained into muscle memory. The movement was fluid, effortless, a testament to the training she had once struggled through.
Her breath came in ragged bursts, forming thick, misty clouds before her face. The ice licked at her skin, biting deep, but the fire in her veins—the sheer, unrelenting fury that propelled her forward—burned hotter.
She wasn’t stopping. Not now. Not ever.
“You are fast, aren’t you? But that is too bad. You can’t kill demons just by stabbing them. It’s the neck you should aim for.”
Shinobu’s grip on her sword tightened, her voice like steel. “Maybe I won’t be able to kill you with stab wounds… but what about poison?”
The scent of blood filled the air, thick and metallic, seeping into her lungs, but she didn’t flinch. She wanted to carve out his other eye, to cut the grin off his face, to make him feel even a fraction of the agony he had inflicted—on her, on Kanae, on so many others.
And then it began.
A low gurgle bubbled up from Douma’s throat, his smirk wavering as his fingers twitched against the wound. His breath hitched. A thin trickle of blood spilled from the corner of his lips, dark and viscous, before he lurched forward with a violent cough.
The sound was wet, raw.
More blood spattered from his mouth, splashing onto the wooden platform in thick, ugly blotches. His body convulsed slightly, his lungs rattling with each breath as if something was gnawing at him from the inside. Another cough tore from him, this time stronger, the force of it making him double over as fresh blood gushed from his lips.
Shinobu wasn’t sure if the poison would be enough—if it would work—but she hoped it would. She had to. Every fiber of her being, every ounce of hatred and grief that had shaped her since Kanae’s death, willed it to be true. Please… let this be enough.
Douma’s lips quirked upward again, even as thick, crimson blood dripped down his pale cheek, splattering onto the ice-coated floor. The contrast was almost poetic—the warmth of his blood against the frigid air, the very thing that gave him life leaking away as if the castle itself rejected his existence. And yet, he remained unfazed.
“This is stronger than the one you used on Rui-kun’s mountain,” he mused, tilting his head as if he were sampling fine wine rather than bleeding and rotting from the inside out.
Shinobu’s breath came in shallow gasps, her pulse hammering against her ribs. They share information. The poison was a double-edged sword—every attempt to perfect it made her stronger, but it also made them more dangerous. The more they learned, the more of a threat they became. If they could break it down faster than she could refine it, then all her work—all the painstaking hours spent experimenting, adjusting, and perfecting her toxins—could be undone in an instant.
“The mixture can be adapted to each demon,” Douma continued, his voice light, conversational—mocking. A wet cough rattled from his throat, thick and congested. He lifted a hand to his mouth, and when he pulled it away, fresh blood smeared his fingers. The sight should have pleased her. It should have filled her with satisfaction. But his face twisted into something that was almost amused, almost delighted.
“Ah… Looks like I was able to break down the poison. I’m sorry.”
A fresh wave of cold crashed over her, but this time, it had nothing to do with Douma’s ice.
And then, right before her eyes, his wounds began to close. The flesh stitched itself together, knitting over with unnatural ease. The bleeding slowed, then stopped entirely. His skin, flawless once more, his eye perfectly unharmed again, he held not a single trace of the damage she had inflicted.
Shinobu’s grip on her sword tightened, her knuckles turning bone-white. She wasn’t done. Not by a long shot.
She had poured everything into that formula—years of research, countless trials, relentless effort. It had been created to be her greatest weapon, her only means of evening the playing field against demons stronger, faster, and more resilient than any human could ever hope to be. And yet, he stood before her, grinning, as if she had done nothing at all.
“I know you tried very hard to achieve this,” Douma continued, voice dripping with honeyed amusement. He lifted a finger, pointing toward her blade. “Your sword—it makes a very strange sound when it’s sheathed. Is that when you change the poison mixture?”
His smile widened, his empty eyes gleaming like fractured glass. “Oh! This is fun! It’s interesting to be attacked with poison! I might end up liking it.” He laughed, lighthearted and careless, clapping as if she had simply gifted him an entertaining distraction rather than attempted to kill him.
“Hey, do you think the next mixture will work? Try it.”
Shinobu’s nails dug into the hilt of her sword, her breath shuddering past gritted teeth.
He was mocking her. Mocking Kanae’s death. Mocking every second of agony her sister had endured.
“Well, that’s fine by me. I personally expected something like this to happen,” she replied, her voice steady despite the fire raging inside her. It burned hotter, consuming every doubt, every lingering hesitation. If this wasn’t enough, she would find a way to make it enough. She had no other choice.
Five times she had altered the poison. Five times she had failed. Each attempt had been met with the same cruel outcome—the toxin lost its potency, its effects diminishing, barely slowing him down. Meanwhile, she was unraveling. The icy air clawed at her lungs, making every breath a struggle. Sweat slicked her skin despite the numbing cold, her limbs trembling from exertion, from frustration. She was running out of options. She was achieving nothing at all.
Maybe—just maybe—she could have accomplished something if she had been stronger. If her hands weren’t so small. If she had kept growing like her sister had. If she were just a little taller, just a little sturdier, maybe she could have reached his neck, severed his head before he had the chance to react. If she had more muscle, more power behind her strikes… maybe he would have been the one bleeding. Maybe he would have fallen first.
But he hadn’t.
And now it was her on the floor, her vision swimming, her chest splitting open as searing pain tore through her body.
Shinobu barely registered the moment Douma's fan tore through her flesh, carving a deep, merciless wound from her shoulder to her ribs. The force sent her to her hands and knees to the cold ground. For a moment, there was nothing—no pain, no sound, just the distant awareness that something had gone terribly wrong. Then, all at once, the pain caught up to her, a searing, unbearable fire blooming inside her.
She gasped, but the breath barely came.
Something was wrong—terribly, terribly wrong. Her lungs struggled against the weight pressing down on them, her body refusing to obey the desperate demand for air. A wet, gurgling cough forced its way past her lips, the taste of iron flooding her mouth. Blood. Too much blood. It pooled beneath her, soaking into her uniform, sticky and warm. Her fingers trembled as she tried to push herself up, but her strength had left her, drained along with the crimson spilling from her body.
She couldn’t stand.
She couldn’t breathe.
Death loomed above her, a silent, suffocating threat. Was this how she died? Here, in this frozen hell, watching her own blood seep into the cracks of the floor while that monster watched with that sickening, empty smile? Just the thought sent a wave of something dark and bitter through her. She had prepared herself for death—had accepted it long ago—but not like this. Not bleeding out on the floor, powerless, with nothing to show for it. If she had to fall, her death had to mean something. Otherwise, what was the point of all the pain, all the struggle?
A violent shudder wracked her body, though whether it was from the cold or the sheer, overwhelming agony clawing through her, she couldn’t tell. Her chest was torn open, her lungs struggling to expand, each breath shallow and sharp. The blood loss left her limbs numb, a dangerous kind of weight settling over her muscles, like she was sinking—like she could simply close her eyes and let the darkness take her. But she clenched her teeth, fingers twitching against the blood-slick floor, willing herself to move. Yet no matter how hard she tried, her body remained frozen, unresponsive, as if it no longer belonged to her.
"Stand up and stop crying."
The words sliced through the haze of pain, and for a moment, she wasn’t sure if she had imagined them. The voice was gentle yet firm, warm in a way that no amount of ice or agony could touch. She knew it instantly. Kanae.
Her breath hitched as she blinked, her vision unfocused, the world tilting in and out of clarity. And then she saw her—standing just beyond the edges of reality, bathed in a soft glow, untouched by the battle, the suffering, the death. Kanae’s violet eyes were kind, but there was no pity in them, only quiet expectation, as if she had never once doubted that Shinobu would rise again.
"Stand up."
Shinobu tried to respond, but her throat was raw, her lungs barely cooperating. She gasped, the taste of iron thick on her tongue. "I— I can’t breathe..." The words left her lips in a fragile whisper, broken, weak, almost too quiet to hear.
"I don’t care." Kanae’s voice remained steady, unwavering. "Stand up, Kocho Shinobu. Insect Hashira."
Her throat burned as she swallowed hard, trying to push down the overwhelming sense of despair threatening to pull her under. She wanted to make Kanae proud. She wanted to avenge her. But she also wanted—so desperately—to let go, to close her eyes, just for a little while, to sink into the warmth of her sister’s presence and forget about the pain, the cold, the blood pooling beneath her. But Kanae wouldn’t let her.
"When you set your sights on defeating a demon, do it. When you decide to win, then win. Win at all costs. You made that promise to me and Kanao, remember?" Kanae knelt before her, lowering herself to Shinobu’s level, her head tilting slightly, just as she had done when Shinobu was the little girl who clung to her sleeve. There was no anger, no disappointment—only certainty, an unshakable truth, as if the thought of Shinobu doing anything but fighting, anything but winning, was unthinkable.
A shadow loomed over her, and the moment of warmth shattered like fragile glass.
"I'm so sorry, it wasn't a clean cut. That’s why you're suffering." Douma’s voice slithered through the air, each slow, deliberate step sending cracks through the blood-streaked wood beneath his feet. His tone was light, almost playful, but she could hear the smug satisfaction beneath it, the amusement in the way he observed her struggling to even breathe.
A fresh wave of pain wracked Shinobu’s body, but this time, she bit down on the scream before it could escape her lips. She would not let him have the satisfaction. Her fingers twitched, weak and trembling, but they moved, pressing against the slick, icy floor.
"Shinobu, you can do it. So try harder."
Her entire body screamed in protest, her lungs burning, her vision darkening at the edges, the weight of her wounds pinning her down. She couldn’t breathe. She couldn’t move. The logical part of her knew that standing was impossible.
But she wasn’t done. Not yet.
Some girls spent their lives searching for a knight, dreaming of someone to save them. But Shinobu had never been one of them. She had never needed a savior—her only true enemy had always been herself. She didn’t long for protection; she had always searched for a sword.
And now, Kanae was crying for her, holding her hand, waiting for her. She would not let her down.
With a trembling breath, Shinobu forced her fingers to tighten around the hilt of her sword. She could still hold it. She had to hold it. Her short, trimmed nails dug into her palm, the sharp sting grounding her, pushing her past the suffocating pain—just as Tomioka always did.
And then, with every ounce of strength left in her battered, broken body—
She stood.