Prologue: The Last Cry of Dawn

Final Battle Against Muzan

He was going to die.

Iguro Obanai knew it; he didn't need to see it. And, truthfully, he couldn't see anymore. Protecting Kamado in the heat of battle had left him blind, and at that moment, he didn't even want to see anything. Everything around him was a storm of death and despair. If there was anything he would miss, he thought, it would be seeing Muzan's face of horror when they finally destroyed him.

Because whatever happened, this would be his end.

The sound of steel clashing, explosions of demonic energy, and the agonizing screams of his comrades filled the air. It was as if the world itself was letting out its last breath. Iguro, with every muscle in his body aching and on the brink of collapse, could barely stand. But it didn't matter. His will remained as strong as the blade of his sword.

Beside him, Tomioka, Sanemi, and Tanjiro attacked relentlessly, like a hurricane refusing to dissipate. But amidst the chaos, Iguro allowed himself a moment to think of those who were not there. Where were the others? The crows had delivered news of their deaths, but Iguro didn't want to believe it. They could be alive, but in Iguro's heart, he felt death was the only explanation; otherwise, none of them would have missed the chance to be here.

Many names shattered in his thoughts: Genya, Shinobu, Tokito... their sacrifices had been as raw as they were brave. In many cases, there wasn't even a body to bury, and those with bodies would be lost in that cursed castle.

These thoughts led him to reflect on his own losses, and only one surfaced immediately, as clear as an open wound: Mitsuri Kanroji.

The Love Hashira had fought alongside him. Her strength and bravery had shone brightly in the darkness of battle, tearing off one of Muzan's arms before falling. Iguro could almost feel her smile as she did it—a ray of light in the midst of hell. But then, she too had fallen. Mitsuri had been gravely wounded… and while Iguro's heart refused to accept it, he knew the chances of her survival were slim.

Why Kanroji? The question pierced his mind, burning more than any wound Muzan could inflict. Why not me? I'm a damned piece of trash… she was the opposite. She was light, strength. Everything I never was.

A scream escaped his throat, visceral and filled with rage. With a precise movement, Iguro plunged his sword into Muzan's side, driving it in with all the fury and despair he could muster. The blade pierced his immortal flesh, but it wasn't enough. It couldn't be enough. Iguro twisted the sword, feeling Muzan's body resist, as if trying to steal more than his physical strength.

"Forgive me, please…" His mind filled with the green and pink hair of Mitsuri, her smile illuminating everything around her, even in the darkest moments. "I wasn't able to protect you. I wasn't enough."

His hands trembled as they gripped the hilt of the sword, twisting it with renewed strength, as if with each turn he could erase his own guilt. He thought of all who had fought for the same cause—those still standing, and those who were no longer part of the world. "In another life perhaps I'll be able to be a better person."

"Do you think you can defeat me!?" roared Muzan, his voice a thunder that shook the castle ruins. "You know nothing about me!"

And then, something changed.

Iguro couldn't see it, but he felt it. A shockwave burst from Muzan's body, a force that resonated as if the very air was crying out in pain. He heard his comrades scream, their voices cut off by the intensity of the explosion. But he didn't fall. His sword, deeply embedded in Muzan, kept him anchored in place.

Pain tore through him like a thousand daggers; his bones creaked under the crushing pressure. It was as if the weight of the world itself collapsed upon him. But he didn't let go of the sword. He couldn't.

And then he felt something else: a cold hand on his back. The sensation paralyzed him as much as the pain coursing through him.

"You shouldn't be here, Slayer," he heard Muzan murmur, his voice like a venomous whisper on the wind.

Iguro tried to speak, respond, scream, but his body didn't obey him. Suddenly, the world around him began to collapse. The sounds faded, leaving a silence more terrifying than any scream. Darkness enveloped him like a shroud, and he felt himself falling.

What… is… happening?

Before finishing the question in his mind, a sharp pain tore through his head. It was as if a thousand memories compressed into a single instant, and then… nothing. Everything disappeared.

His eyes opened in surprise, and he moved so quickly he hit the wall. The impact resonated in the tranquil air, an echo contrasting with the chaos of the battle he had left behind. The confusion was so intense that Iguro jumped back, his sword already in hand, expecting Muzan or another demon to appear before him. But all he saw was… a wall.

For a moment, Iguro thought he had died. Is this heaven?

"Where…?" Iguro whispered, his voice barely choked a murmur. His mind was completely out of control, and for an instant, he didn't even know where he was.

Something moved beside him, and the familiar figure of Kaburamaru appeared before him, dragging something in its jaws. The serpent was an anchor in the storm of emotions surrounding him—a reminder that, at least, he wasn't completely alone.

Iguro lowered his sword and watched as Kaburamaru pushed an object towards him. When his gaze focused on the calendar, his body tensed. It was the same one he always carried with him, marked with mission dates, personal notes about Kanroji's letters, and little details that organized his life. But there was something more—something that completely captured Iguro's attention: the last marked date was…

The date when Tanjiro Kamado and his demon sister, Nezuko, would arrive at the Ubuyashiki Mansion to be judged by the Hashira.

The air seemed to vanish from his surroundings as Iguro tried to comprehend what he was seeing. A demon slayer's mind was trained to focus on logic, on combat details, but this moment shattered him. How was this possible? How could he be in…

"Oh no… oh crap."

The words escaped his mouth as he skimmed through the calendar notes, searching for answers that didn't exist. There was nothing recorded after that date, as if the future was completely blocked.

He had gone back in time.

"You shouldn't be here…"

Muzan's words echoed in his mind like distant thunder. Now he remembered the venomous whisper he had heard during the battle, when the world seemed to collapse around him. Was this Muzan's doing? Iguro thought, his blood turning completely cold.

If it was, then it was a ploy to alter the flow of time and reverse everything they had accomplished. Every death, every sacrifice… all of it would have been in vain.

A memory slipped into his mind, one that hit him with even greater force than his revelation.

"No, please! Don't die, Iguro-san!"

The last words of Mitsuri Kanroji, accompanied by her desperate cries, were now only wind, swept away by Muzan's power and his curse. In that moment, Iguro couldn't contain himself. All the hope he had accumulated, everything he had fought to protect… felt like ashes in his hands. He wanted to scream, tear apart the calm surrounding him with the rage boiling inside him.

He was alive. And the demons were too.

Sensing his rage, Kaburamaru slithered along his arm and settled on his shoulders. There, the serpent placed its head close to Iguro's, hissing with a calmness that, curiously, restored the Serpent Hashira's sense of direction.

"You're right," Iguro said, looking at his serpent as he regained control. "They've returned, but so have we."

A thought emerged from the ashes of his despair: he could use what he knew to his advantage. He had seen the future. He had lived through the destruction, the sacrifice, and the pain that Muzan would bring. But he had also seen the strength of his comrades, the hope that would form through their bonds.

He was terrified of showing vulnerability in front of others. His past had never allowed him to fully trust anyone, and although he didn't understand why his comrades would want to spend time with him, he now knew he would have to change. He would have to be better.

Not only defeating Muzan depended on this, but also bringing the peace that this world so desperately longed for.