Greatest Spy Reincarnated Into Another World

On January 5th, 2025, in Tokyo, Japan, the final car of the high-speed bullet train housed an unexpected visitor. Armed with specialized suction gear, the intruder clung perilously to the train's exterior, slowly making their way up toward the compartment entrance.

Once at the door, the intruder stealthily slipped inside without a sound. They crouched low, skillfully using the shadows and seats for concealment.

Positioned at the front was a man dressed in a black suit and matching fedora, seemingly oblivious to the intruder's presence.

"Damn that boss… What's the point of having us supervise each carriage individually when the whole train has been reserved? No one else is here except us…" the man in the suit grumbled, unaware of the looming threat.

Exploiting the distraction, the intruder moved with ghostlike finesse, closing in from the man's blind spot. 

"Huh?"

By the time he caught on, it was too late—the intruder struck his chin, rendering him unconscious.

Thud!

With a finger over his earpiece, the infiltrator gazed at the door leading to the next compartment. 

"Dawn to HQ, I've successfully breached the last compartment…" The intruder reported, exhaling a sigh of relief. "I thought I was going to die out there…"

<Copy that, Dawn. The enemy could be anywhere; proceed with caution.>

"Will do," Dawn replied, glancing down at the unconscious man on the floor. "I'll change my disguise."

-

-

-

Suddenly, the compartment door swung open, revealing the man in the black suit who had previously been incapacitated.

Adjusting his blazer, he looked exactly as he had before, except for the addition of a monocle. Dawn's disguise was impeccable.

He proceeded to the next compartment, finding it unexpectedly empty.

<<Compartment ten, any activity there? Any signs of intruders?>>

A voice crackled through the communication device attached to Dawn's suit. Clearing his throat and altering his voice, Dawn responded.

"All clear here."

He had not only perfectly mimicked the voice of the man he had neutralized, but the accent as well.

<<Alright, remain in your compartment until further instructions.>>

He turned off the device and positioned himself by the entrance to the next compartment, spotting another target through the door.

"Stand by… I wish I could. Unfortunately, I have a mission to complete," Dawn murmured, with a nervous smile.

-

In a dimly lit room arrayed with large monitors on the walls, a group of individuals scrutinized the video feed from Dawn's monocle while simultaneously monitoring his vital stats.

"Sir, are you sure it's enough to just send him? This mission has the highest classification. If he fails to prevent the prototype from reaching the north, the consequences would be…" The woman adjusted her glasses, worry creasing her brow.

From the higher end of the room, where only his silhouette could be distinguished, an elderly man responded with a grin. "It will be fine. Sending multiple agents would raise suspicions. Besides, that man alone is worth a dozen spies."

"More than a dozen spies? But his vitals indicate that he's terrified. He has been trembling since the moment he infiltrated–"

"This is your first time witnessing one of his missions in action, isn't it?"

With her gaze on the screen showing the feed from the monocle, she nodded slowly. "Yes, sir."

"…I am aware of his state… I have also met him in person. That man is a coward, scared by the slightest things. Yet despite this flaw, he has never failed a mission."

"Codename Dawn; he's the greatest spy in our organization… and I dare say, in the world."

"The greatest…? But he looks so young…?" She asked.

"Don't let appearances fool you; he is a master of many arts, including disguise. Although he works for us, we know nothing of his actual appearance or age…" The old man's grin broadened. "There are no records of him anywhere; he's like a ghost."

"A ghost…"

Though her face remained expressionless, it was evident that what she'd heard had left a profound impression.

"This extraordinary man is the one who has chosen to take on this mission. Let's not worry and place our faith in him."

-

Dawn cleared each compartment of the train, swiftly neutralizing any adversary he encountered. His actions were so smooth that his infiltration went unnoticed.

Finally, he arrived at the last compartment before the driver's cabin, where two men in black suits stood as sentinels. On spotting Dawn in his disguise, they immediately tensed.

"What are you doing here, number 5? This isn't your assigned compartment… and why the monocle-"

Before they could finish their sentence, Dawn had closed the distance between them, thrusting his palm up at the left man's chin while simultaneously delivering a swift kick to the chin of the other. 

Thud!

As their bodies dropped simultaneously, Dawn quickly pushed through to the driver's cabin.

At first glance, the compartment appeared dark, cold, and deserted. However, as Dawn stepped inside, the lights flickered on, revealing a ring of black-suited men surrounding him, each with a pistol aimed at his head.

"Don't move; we won't hesitate to shoot," warned the man seated at the driver's seat.

Dawn froze, his expression morphing into one of fear as he began to tremble.

"Haa… I thought our plan for the prototype transport was perfect. Yet, a mouse managed to sneak in... Look at him. He's scared shitless."

The speaker, presumably the group's leader, was a man with slick jet-black hair and intimidating black eyes. A distinctive-looking katana was strapped to his waist and beside him sat a large silver suitcase—the exact item Dawn had been assigned to retrieve.

"Well, who wouldn't be scared with all these guns aimed at them…" Dawn responded nervously.

The leader stroked his clean-shaven chin as if arriving at a realization. "Hmm… good point. But more importantly, you've got some nerve hijacking a train under my, the Silent Viper's jurisdiction."

The Silent Viper was a notorious global criminal with a bounty surpassing $1,000,000. From assassinations to trafficking, he dabbled in it all.

"Tell me who you are and I might let you live."

"Who am I...? That's something I'm still trying to figure out to this day," responded Dawn, plastering on a fearful smile.

"Hahaha...! He's trying to figure it out, he says! Can you believe this guy? Haha."

When they started laughing, Dawn nervously joined in.

"Ha...haha-"

Suddenly, the leader's laughter ceased, replaced by a bored expression. "Kill him."

In that instant, they all pulled their triggers simultaneously.

Shatter!

But instead of bullets firing, their pistols broke apart in their hands.

"Wha-"

Bam!

While they were confused, Dawn's right foot rocketed upward, slamming into the chin of the nearest suit-clad individual and knocking him out cold. With a lithe spin, he delivered a flurry of attacks to the others.

Chin, liver, temple, solar plexus, and Adam's apple. Each strike targeted a vital spot. All but one of them collapsed instantly. 

The remaining man lunged at Dawn with a desperate tackle.

Reacting agilely, Dawn sidestepped and drove his knee into the man's face.

Crunch!

The sound of crunching bone echoed, followed by the thud of his body hitting the ground. Just like that, the group had been neutralized.

"That only leaves-"

A bright flash caught Dawn's eye, interrupting his thought. He immediately ducked. Less than a second later, a beam of light sliced through the cabin, sailing just above his head.

Looking towards the source, he saw their leader holding the suitcase in one hand, a drawn katana in the other. The blade of the katana glowed a bright, ethereal red, unlike any normal sword Dawn had ever seen. 

"This is another tool they developed, isn't it impressive? It doesn't matter how strong you are, against this weapon, you're nothing!" He declared, assuming a sword stance.

Positioning himself to attack Dawn again, the leader placed his left foot forward, gripping his katana tightly before initiating another swing.

Bzzt!

The sword traced a perfectly straight line, its beam slicing through walls as effortlessly as through butter as it sped toward Dawn.

Just before it made contact, Dawn's figure blurred, his silhouette reappearing behind the leader.

A cold shiver ran down the leader's spine, and he spun around to attack again, but his movement stopped midway. He felt something wrong with his body.

Looking down, his eyes widened. The white shirt of his black suit had a deep hole in the chest, quickly staining red as his body registered the injury.

"A spy doesn't kill unless it's absolutely necessary… I would have preferred to avoid this, but I saw no alternative," Dawn declared, a nervous smile on his face as he averted his gaze. "I'm sorry."

A quick glance at Dawn was enough to reveal what was missing from his body—his heart. It pulsed slowly in Dawn's hand as if not yet realizing it was no longer inside its host.

[Killer Spy Arts: Heart Removal.]

Gasping for breath, the leader reached out toward his own heart, trying to reclaim it.

"You… damn monster…"

Those were his final words before he collapsed. Meanwhile, Dawn dropped the heart onto the floor, picked up the suitcase beside the lifeless leader, and opened it to inspect the contents.

Inside was a single item, a large spike-shaped crystal emitting a pulsating crimson light. Seeing this, Dawn breathed a sigh of relief.

"Um... HQ, this is Dawn. I've secured the prototype… Can I head back now?"

<Copy that, you may retreat.>

Upon receiving confirmation, Dawn was about to close the case when suddenly-

Drip!

A drop of his blood, which had trickled down his chin, fell onto the crystal. The moment it touched, everything inside the room began to levitate as the crystal pulsed with an intensifying glow.

"Uh… HQ, the crystal is glowing. I don't think this is supposed to happen, awaiting further instructions!"

<C- Ad- Da- Fai->

In the midst of grabbing the floating suitcase, the communication from his earpiece began to distort. The prototype was interfering with the frequency.

Surprised by the sudden loss of gravity and the chaotic developments, he glanced out the window and noticed the scenery shifting rapidly as the train accelerated.

"What the- what on earth is happening?!"

In desperation, Dawn pulled the glowing crystal from the suitcase, inspecting it for some form of deactivation method, but found no clues.

The world outside the window descended into darkness as the train entered what appeared to be a tunnel, increasing in speed even more.

"Ah… damn it. I knew I should've turned down this mission-"

Blinding lights filled his vision and then everything went pitch black.