One Piece: Start with Zanpakutō

The next morning.

Not long after Rosen left the Navy dormitory, he ran into Gion and Tokikake, who were headed toward the teaching building.

"Good morning, Rosen."

Gion greeted him with a gentle smile.

"Hey! Brother, don't slack off!"

Tokikake strutted over proudly. "Just so you know, Gion and I both mastered Observation Haki yesterday!"

"If we fought again today, maybe you wouldn't be able to defeat both of us before your Haki ran dry."

He puffed out his chest, trying to look confident — but his eyes still flickered with a hint of caution.

"Is that so?"

Rosen gave a faint, easy smile. "Congratulations! You too, Gion."

Tokikake was stunned.

Why was he congratulating them so sincerely?!

Gion, on the other hand, merely looked down, her fingers tightening slightly around the hilt of her sword.

She knew better than anyone: Even with Observation Haki, they would not truly close the gap.

"By the way… where are you off to?" Gion asked, forcing her voice to sound casual.

"I'm not sure," Rosen replied. "Teacher Zephyr said that yesterday afternoon's class was my last here at the Academy. He told me to meet him at the Academy gate this morning."

"Last… class?"

"You— You're not graduating already, are you?!"

Gion and Tokikake nearly shouted in unison, eyes wide.

"No, no."

"From what he said, it just means there's nothing more he can teach me here. I think he plans to take me somewhere else for further training."

Rosen waved lightly as he started walking.

"Two days…"

"Four classes… and already done with the Academy?"

Tokikake's jaw nearly hit the ground.

Even the current Admiral candidate had stayed at the Academy for nearly a year before finally going out for practical training at sea.

But Rosen?

Four classes.

Two days.

And Zephyr himself declared he had nothing left to teach.

"Could it be… after yesterday's class, he's grown even further?"

Tokikake shivered at the thought, suddenly feeling like his earlier boast wasn't cowardly enough.

"Let's stop here."

"Otherwise, if you're late, Teacher Zephyr will scold you."

Gion pulled Tokikake lightly, but her eyes never left Rosen's departure.

"Ever since meeting Vice Admiral Tsuru, and hearing Garp and the others call me a 'monster' with the potential of an Admiral, I always thought I was special."

Gion's voice was soft, almost lost to the wind.

"But now… compared to him, I feel like just an ordinary person."

"If monsters have rankings…"

Tokikake sighed deeply.

"Then Rosen is at the absolute top. The so-called threshold of an Admiral — that's just the bare minimum to even stand before him."

Gion didn't reply.

The silence between them was enough.

Meanwhile,

After parting ways, Rosen walked to the Academy gate and waited quietly.

Not long after, Zephyr appeared, draped in his Justice cloak, striding forward like a mountain.

"Let's go."

Zephyr's voice was calm, yet each word carried a heavy force.

"Teacher Zephyr, where are we going?"

Rosen followed alongside him, curious.

"To your fifth lesson."

"A place that imprisons all the filth and darkness of this world."

"Impel Down."

Rosen paused mid-step, then smiled lightly.

"You want me to spar with the prisoners there?"

"No."

Zephyr didn't even turn his head.

"I want you to kill them. With unwavering resolve."

"Can you do that?"

"Why not?"

Rosen shrugged easily.

"You don't feel any burden? Even if they're criminals, they're still… people."

Zephyr's voice softened slightly.

Had he been wrong about this student? Was he another idealist dreaming of "clean justice"?

"Killing people? No problem."

"Killing animals? I might hesitate."

Rosen's gaze was unwavering, his voice clear.

Who exactly were those locked away in Impel Down?

Monsters.

The only blemish on Luffy's record was freeing those prisoners.

Those clowns Buggy led out — were they truly human?

Zephyr stopped for a moment, then burst into hearty laughter.

"Good! Good! That's exactly it!"

"When we get to Impel Down, show no mercy. No pity. No forgiveness."

"The Navy's compassion and kindness are luxuries we cannot afford."

"Mercy is God's business. My job is to send them to meet Him."

Rosen's lips curled into a faint smirk.

"Perfect mindset."

"When we get there, all you need to do is fight, eat, grow, and sleep."

"Every battle will sharpen your skills, push your Haki to its limits, and refine everything you've learned and created so far."

"Rather than letting those scum waste our air and rations, it's far better to let them serve as fuel for your rise."

Zephyr's voice grew firm again, eyes shining with approval.

"Which floor will I be fighting on?"

Rosen glanced at the imposing ships lined up at the dock.

They loomed like giant sea beasts, their iron hulls glinting under the morning sun.

"The sixth floor."

"Infinite Hell…?"

Rosen's eyes sparkled, not with fear — but anticipation.

The sixth floor: a place where monsters so dangerous they were "erased from history" rotted away.

Killing them?

A favor to the Navy.

A gift to the entire sea.

As they boarded the ship, a lazy yet piercing voice drifted over.

"We meet again… junior."

A familiar figure approached, wearing that perpetual half-smirk.

"Vice Admiral Kizaru."

Rosen greeted politely, though his brow arched slightly.

"Don't look so surprised."

"Zephyr-sensei's training schedule for you is a little too… extreme."

"The prisoners on the sixth floor are far worse than you can imagine. They'd rather die or destroy everything than cooperate."

"So… Fleet Admiral Sengoku asked me to tag along. Just in case."

"Think of me as a spectator. You can focus on your slaughter."

As he spoke, Borsalino handed Rosen two small notebooks.

"What's this?"

Rosen flipped them open.

His sharp eyes immediately understood, They contained detailed profiles — bounties, crimes, abilities — of the prisoners on the sixth floor.

If these monsters chose to escape instead of fight, or started destroying the prison…

Even Zephyr, after years of retirement and weakened health, might struggle to contain the chaos.

But with Borsalino here…

An Admiral candidate who had honed every aspect — physical prowess, Haki, swordsmanship, and his deadly Pika Pika no Mi.

As long as two or more "Admiral-level" monsters didn't escape at once…

There would be no chaos that couldn't be quelled.

The warship set sail, slicing through the morning mist toward that abyss of endless screams.

... 

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