A Device is the crystallization of one's soul and will; it reflects its wielder's very essence.
It takes form based on a Blazer's inner spirit, personal values, aesthetics, personality, and lifestyle. Basically, it reflects their sense of self.
Because of that, it won't change forms easily.
But when a person undergoes a big emotional change, one that transforms who they are fundamentally, that rebuilds them from the inside out, it results in their Device taking on a new form, one shaped by that change.
That phenomenon is called Device Reconstruction.
It's an extremely rare occurrence, so rare, in fact, that even in the light novel Rakudai Kishi no Eiyuutan, it only happened twice.
It signifies a complete shift in a person's heart when they rebuild something vital within themselves.
And that was exactly what happened to Erika.
When she cast aside her fear, hesitation, and self-doubt, she experienced a major character development, one strong enough to cause a Device Reconstruction.
Causing her Device, Églantine, to evolve.
Now, instead of two ribbons, she had six of them, three on each hand.
And that wasn't the only change to her Device either.
Daki, who had been fighting all of them, suddenly felt something new.
Her body tensed as she looked toward Erika and realized… something had changed about her.
"What is this feeling?" Daki thought, narrowing her eyes.
Then it began, her obi slashes started being cut down, one after another.
She froze a little in shock.
Just moments ago, she had been effortlessly pushing them all back. Yet now… something was slicing through her attacks.
Her eyes widened in disbelief. "What's happening!?"
Then she saw it.
It was Erika's ribbons.
There were six of them now, and they were moving at an incredible speed, faster than even Daki's enhanced vision could track.
Not even with her three eyes could she follow them.
They were faster, more accurate, and sharper than her obi.
Daki's expression twisted in shock as she struggled to comprehend it.
"What happened? How did she…?"
Then she noticed something; from those crimson ribbons, she sensed the scent of blood.
Her eyes widened further. "Blood…?"
She thought, "Wait… blood? Are those ribbons coated in blood? Is it her blood? Is that why she can control it better? But how could she control blood? What in the hell even is she…?"
Yes, Églantine's reconstructed form was now directly linked to Erika's blood.
All of her ribbons were coated in it, allowing her to control them far more precisely than before.
Their speed, sharpness, and accuracy had already surpassed Daki's obi.
So even though Daki had more obi than Erika's six ribbons, she was being completely overwhelmed by Erika's sheer speed and power.
The six crimson ribbons danced in the air like living blades, faster and deadlier than Daki's. Erika's attacks had become so fast that even Tanjiro, Zenitsu, and Inosuke, who were fighting beside her, didn't even have the chance to jump in.
Within moments, Erika's ribbons shredded most of Daki's obi slashes.
Then Erika whispered with a cold and resolute tone. "Blood Breathing, First Form — Crimson Thorn Prison."
Her ribbons lashed out, glowing with crimson energy, and completely bound Daki's body.
The force of gravity magic pressed down on her, crushing her limbs and torso until only her head was left exposed.
"Gah…! W-What is this!?" Daki screamed, struggling to move but finding her entire body immobilized by the tightening ribbons.
Tanjiro's eyes widened as he saw the opportunity. "Now's our chance! All of us, together!" he shouted.
Inosuke grinned beneath his boar mask. "Yeah! Let's end this flashy! Don't fall behind my underlings."
Even Zenitsu, still asleep, said resolutely, "Yes, let's finish this."
He vanished in a flash of yellow lightning.
"Thunder Breathing, First Form — Thunderclap and Flash!"
Inosuke followed with a roar, swinging both his serrated swords.
"Beast Breathing, Second Fang — Slice!"
And Tanjiro charged in right behind them, flames bursting from his sword as he shouted, "Hinokami Kagura — Dance!"
Their coordinated strikes blazed forward toward Daki's bound form.
Meanwhile, Akira, who was fighting Gyutaro alongside Tengen, suddenly heard Selena's telepathic voice echo in his mind.
"Brother, they're about to finish her!"
Akira turned his head slightly, catching a glimpse of Tanjiro and the others preparing to cut off Daki's head. He smirked. "Guess it's time to get serious."
Beside him, Tengen, who was already clashing with Gyutaro, shouted,
"Sound Breathing, Fourth Form — Constant Resounding Slashes!"
He unleashed a dazzling barrage of attacks, his twin swords spinning in a storm of flashing steel and rhythm.
Gyutaro smirked, countering with his own technique.
"Blood Demon Art — Rampant Arc Rampage!"
He flailed his Kama wildly, generating a dome of sickle-shaped blades of solidified blood around himself. The blades spun at such speed that no opening remained, expanding outward with a violent burst that forced even Tengen back.
Akira exhaled and finally put away his massive Demon Slayer sword, pulling out his twin katanas from his inventory.
He took a deep breath. And activated Star breathing for the first time in this fight, he didn't use it with the demon slayer sword because that thing is too expensive, he seriously didn't want to break that.
So, he decided to use it with his twin katanas; the star breathing he created had only one form, mostly because he had confidence he could finish the fight with that single form.
Holding his twin katanas, he murmured, "Star Breathing, First Form…"
The twin katanas lit up with bright purple light, glowing like a superheated purple plasma.
At the same time, Tengen, now overwhelmed, was pushed back as Gyutaro turned his attention toward Akira.
"Flashing Comet," Akira said as his body flickered.
In an instant, Akira vanished from sight.
A blinding flash ripped across the battlefield, twin trails of purple light streaked through the air like the tails of a comet.
A single booming sound followed.
Gyutaro's eyes widen in shock as his head separated cleanly from his body and flew through the air.
At that same moment, on the other side of the battlefield, Tanjiro, Zenitsu, and Inosuke's combined assault cleaved through Daki's neck, even as she tried to turn it into an obi.
And as if guided by fate itself, the two severed heads, Gyutaro's and Daki's, flew through the air and landed side by side, their expressions frozen in disbelief.
Akira lowered his blades as they both shattered like broken glass, and he sighed. "I seriously need to find a way to use it without breaking my swords, as for the rest. Well… that went well, I guess."
But then, his expression suddenly changed. His eyes widened as he turned toward Gyutaro's body.
"Wait… oh no."
He had completely forgotten about the demon's self-destruct.
"Crap!" he muttered, sprinting toward the corpse, hoping to throw it away before it detonated. But it was already too late, the body began to swell, veins pulsing with dark red energy as a surge of blood burst outward, about to explode in all directions.
Akira instinctively raised his arm and shielded his face. "SHIIIIIII…..!"
But… the explosion never came.
He slowly opened his eyes, only to see Gyutaro's blood that is erupting from his body, frozen. As if they are frozen in time itself.
And there, just a few meters ahead, stood Erika, her ribbons extended and touching the blood. She was breathing heavily, and her face was pale with exhaustion.
Akira blinked in surprise. "She… used blood manipulation to stop it?" he murmured to himself. "Since when did she learn that…?"
Needless to say, he completely missed her character development and Device reconstruction.
He wanted to ask how she did it, but he decided to ask later.
For now, he dropped to the ground, exhausted. "Ohhh… we're saved."
Erika, still catching her breath, slowly let her ribbons fall, and as her device disappeared, the frozen blood lost its energy and splattered harmlessly onto the ground. She sat down on the ground, looking completely drained.
Tengen, who had been bracing for the explosion as well, finally relaxed and let out a laugh.
"Whew… I almost thought I died there!"
Akira nodded. "Oh, right, we're still poisoned, by the way."
"Yeah, that too," Tengen said, grimacing. "Got a solution?"
"Well, I…" Akira began, but stopped when a small figure approached.
It was smol Nezuko, she came near him and raised her hand as if greeting him,
"Nezuko?" he said, blinking in surprise. "What is it?"
But without answering, Nezuko just touched his arm, and suddenly, his body was engulfed in pink flames.
"What the…?!" Tengen shouted in alarm.
But Akira didn't move. He stood perfectly still, blinking in confusion. The flames were warm but not painful; instead of burning, he felt something else inside him melting away.
He exhaled softly. "Oh… the poison… it's disappearing."
Tanjiro, who had come closer, nodded and said. "I think… Nezuko's Blood Demon Art ignited the poison inside your body, burning it away. I'm not entirely sure how it works, but… It's amazing."
By then, Nezuko had already turned toward Tengen, who instinctively flinched as she touched his shoulder, and he, too, burst into pink flames.
"Wha…hey! I'm flamboyant!" Tengen shouted, but within seconds, the burning sensation faded, leaving him feeling lighter.
Akira sighed, half amused. "I guess that's handled, then…"
He looked at the battlefield, the remains of the destroyed street, the crumbling buildings, the quiet aftermath. "Now I just need to collect some blood before they vanish. And check on their heads, too."
Tanjiro straightened. "Don't worry, Akira-san, I'll take care of that."
"You sure?" Akira asked, tilting his head.
"Yeah," Tanjiro said firmly. "I can't rest easy until I find them myself."
Akira nodded. "Alright. I'll leave it to you, then."
As Tanjiro moved off to gather samples and confirm the demons' deaths, Akira let out a long breath and finally sat down. He didn't really feel like chasing after heads at the moment; he didn't want to be dragged into Daki's and Gyutaro's flashback, he already knew their sad backstory after all.
Then, his eyes drifted to Erika, who was sitting a short distance away, her body trembling slightly.
He walked over and crouched beside her. "Erika… how are you holding up?"
Erika looked up at him weakly. Her voice was soft, almost like a whisper. "I'm tired… and I need blood. I'm thirsty. And sleepy too… I can't even stand."
Akira smiled faintly and said, "Alright then."
Before she could protest, he gently picked her up, carrying her in a princess hold.
"Then I'll carry you," he said quietly. "You can drink my blood like this, too."
Normally, Erika would have turned red and refused, but right now she was far too exhausted to argue.
So, as Akira held her close, she leaned in, her fangs lightly brushing his neck, and bit down.
Warmth spread through her body as she drank his blood, and for that moment, that was all she needed.
At least right now… that was enough.
Meanwhile, the news of killing the upper moon reached the demon slayer estate. In his quiet room, Ubuyashiki Kagaya slowly lifted his head.
His pale lips curved into a faint smile, one that trembled with exhaustion and joy.
"Is that right…?" he whispered. "They defeated it? An Upper Rank…?"
The words came out half in disbelief, half in wonder. His blind eyes glowed faintly with reflected lantern light as he leaned back against his cushion.
"Good job, Tengen… Tanjiro… Nezuko… Zenitsu… Inosuke…and our guests from afar."
He broke off suddenly, coughing. His hand, thin as porcelain, pressed against his mouth.
A dark stain spread between his fingers.
"Kagaya-sama!" his wife, Amane, cried, leaning close to steady him.
But Kagaya's trembling shoulders shook, not from weakness, but from something brighter. He laughed through the pain, his voice cracking like glass.
"For a hundred years… for a hundred years, nothing had changed!"
He raised his head, his ruined skin illuminated by the lamplight. The curse had eaten away at him, yet his smile seemed to glow through it.
"But now… it has, Amane," he said, breath catching.
"Yes?" she answered softly.
Kagaya's next words came between ragged breaths, flecks of blood staining his lips.
"Do you see? This is an omen. Fate is about to take a dramatic turn! The consequences will be widespread, sweeping up everything around them… shaking them to their very core…"
His hand clenched weakly over his chest.
"And eventually… they will reach that man…"
His voice, though faint, carried a weight that made the candles flicker.
"Kibutsuji Muzan! We will defeat you… without fail… during our generation! You, the sole blemish on my family!"
He coughed again, blood striking the tatami with a soft, terrible sound.
"Children!" Amane called, her composure finally cracking.
"Boil some water! Fetch his medicine and towels, hurry!" she said with urgency in her voice.
His children rushed over, calling out to him.
And far away, in another realm of endless walls and shifting floors, a single figure stirred.
Akaza stood within the glowing red depths of the Infinity Castle, eyes narrowing as the floor rippled beneath his feet.
"This place…" he murmured. "To be summoned here means…"
His hand curled into a fist, the veins beneath his skin glowing faintly.
"An Upper Rank has been killed by the Demon Slayers."