Chapter 2: Kanami Reire: The Isekai Extra
The cold air ripped through Kanami's thin, sweat-soaked clothes. One moment he was a drunken office worker hurling a manga across his dingy apartment, and the next, he was standing in a snowy forest, his body inexplicably younger and fitted with unfamiliar peasant attire. He instinctively brought his hands up to his head, which throbbed with a pain far worse than any hangover.
He stumbled forward a few yards, groaning, his vision swimming. Before he could fall, a clear, sharp, digital "DING!" exploded inside his mind, silencing the pain instantly. It was a sound so precise and unnatural, it seemed to cut the very air, yet only he heard it.
> SYSTEM VOICE (Telepathic): Welcome to the World of Kimetsu no Yaiba. Primary objective: Prevent Key Character Deaths. First Task: Assist Protagonist. Reward: System Status Activation
A translucent, glowing blue panel flickered into existence right in front of Kanami's eyes, hovering like a heads-up display. He, a veteran fan of the "Isekai" genre, recognized the trope immediately. Terror mixed with a strange, dark triumph. He wasn't just here—he was here with cheat codes.
| Name: | Nameless Extra |
|---|---|
| Goal: | Save the Story |
| Inventory: | Strongest Nichirin Sword x1 |
| Mark: | Demon Slayer Mark (Across the Right Eye) x1 |
| Skill: | Otherworldly Swordsmanship (Blood Devour) x1 |
He forced himself to focus on the reality unfolding around the strange blue screen. A few yards away, a small boy, Tanjiro Kamado, was desperately grappling with a stern-faced swordsman, Giyu Tomioka. Giyu, the Water Hashira, had his blade raised, poised to deliver a decisive, lethal blow to the girl Tanjiro was shielding: his demon sister, Nezuko.
Kanami's heart hammered against his ribs. This was the moment of no return. Giyu was about to end the protagonist's quest before it even began. All the future tragedies he knew, the deaths he mourned, all hinged on this single, terrifying second.
Intervention and Power Reveal
The trauma of being cheated on and fired fueled a defiant anger. Kanami gritted his teeth, refusing to let the tragic, messy ending he despised be repeated here at the beginning. He didn't have time to process or plan; instinct and the System's prompt took over.
"Wait! Don't kill her!" Kanami shouted, stumbling forward across the snow. His voice cracked from disuse and panic, but the urgency was real.
Giyu, a master of focus, was momentarily stunned by the sudden, panicked intrusion of the stranger. He redirected his intense, cold gaze to Kanami, his concentration slightly broken. "Stay back, civilian! She is a demon, and my duty is to exterminate her!"
Kanami knew he had to earn the Hashira's respect—or at least his momentary distraction—quickly.
> SYSTEM (Mission Update): Equipping Strongest Nichirin Sword. Activating Demon Slayer dragonic Mark (Right Eye).
>
A tangible pressure built in his right hand, and the heavy weight of a sword materialized in his grasp. It was a pitch-black Nichirin katana with a jagged, unsettling purple guard, its metal radiating a faint, predatory heat.
Simultaneously, an excruciating pressure formed over his right eye. A dark red, dragon-like Demon Slayer Mark—
instantly formed, spreading like a tattoo across his temple and cheek. With the Mark's appearance came a sudden, violent surge of unnatural physical strength and alertness that felt more akin to a demon's power than a human's.
"I know!" Kanami yelled, fighting to control his trembling hands and pointing his newly acquired blade at Giyu. The sight of him having a unique sword made Giyu visibly hesitate. "But she's different! I... I came to help them both! If you're a Demon Slayer, test her yourself! Look at her! She's protecting him!"
Giyu narrowed his eyes, sensing the immense, volatile energy radiating from the stranger. A mere civilian should not possess a Nichirin blade, nor the terrifying, uncanny Aura—an ability only a select few achieve after years of grueling, near-fatal training. The power Kanami held was eerily similar to a Demon's, yet utterly distinct.
This sudden intervention, combined with Giyu's earlier, fleeting observation of Nezuko protecting Tanjiro, was enough to plant the necessary seed of doubt. The timeline had bent, but not completely broken.
The Truce and The Quest
Giyu slowly lowered his sword, though the tension didn't dissipate. He looked first at Nezuko, then at Tanjiro, and finally back to the marked man with the unnatural weapon. He gave Tanjiro the same crucial instruction that would set the true story in motion: Find Sakonji Urokodaki on Mt. Sagiri.
Giyu then turned his full, unblinking focus on Kanami, his expression stern and unforgiving. "You... I don't know who you are or what power you hold. Your Mark appeared out of nowhere, and your sword is unlike any I have ever seen. But your presence here is no coincidence. If you truly wish to help this boy and his sister, then accompany them to Mt. Sagiri."
Giyu paused, his voice dropping to a harsh whisper. "But understand this: I sensed an unnatural, demonic nature to your strength. If that demon sister ever devours a human, the consequences will be yours as well. I will personally hunt you both down."
Kanami, knowing the risks—and the future he was now responsible for—simply nodded, a grim determination setting in. "Understood. I'll make sure they both make it."
With one final, piercing look that promised death if they failed, Giyu Tomioka vanished in a flash of speed, leaving a whirlwind of snow in his wake.
Tanjiro immediately dropped to his knees beside his sister, checking her for injuries. Only then did he turn his attention to the mysterious stranger, staring at Kanami's unique Nichirin sword and the strange, dark-red Mark that still pulsed faintly over his right eye.
"Who... who are you?" Tanjiro asked, still weak, his voice trembling with exhaustion and awe.
Kanami gently sheathed his powerful blade. He looked at Tanjiro, the boy who would become the ultimate protagonist, and the sister he was now sworn to protect. He suppressed the desire to tell the boy he was a fan from the future who hated the ending.
"My name is Kanami Reire," he said simply. "I'm... a traveler. And I'm going with you to Mt. Sagiri. I have a feeling we both have a lot to learn about saving people."
The immediate threat was gone, but the long, arduous journey had just begun. Kanami was now an immediate, immensely powerful, but completely untrained, ally. His system-given power meant he might not need to struggle with the same training Tanjiro did, allowing him to be a mentor or guardian right away, while his Otherworldly Swordsmanship (Blood Devouring) Blood Devouring is not a breathing style but an ability grant by the system, for every slash he made and blood was spilled, it will turn into an essence to make the host stronger, it was a unique, forbidden-feeling power that would define the moral dilemmas and action of his new life.
Kanami is now Tanjiro's traveling companion and unofficial guard. The next steps are clear: travel to Mt. Sagiri and find Urokodaki.