OP: The Flame Pillar Of Justice

Ace steadied his breath as he sensed a presence through the smoke and dust of the explosion.

"Hmm! Your Observation Haki is quite sharp!"

Rengoku burst through the smoke, charging straight at him once again.

With both of their Observation Haki active, even in the obscured battlefield, they could sense each other's positions clearly.

Their weapons—Rengoku's Haki-coated sword and Ace's blazing fists—clashed again and again.

Each of Rengoku's strikes, fueled by Flame Breathing, was heavy and forceful. Ace was slowly losing ground in power, though he made up for it with his superior speed.

"Black Flame Daruma!"

Ace suddenly threw his Haki-clad right hand forward, obscuring Rengoku's vision—and then unleashed a massive explosion right from his palm.

The blast hurled Rengoku back with brute force, but he quickly corrected his stance mid-air and raised his sword once more.

"Flame Breathing, Third Form—"

"Blazing Universe!"

"Mirror Fire!"

Two waves of concentrated flame collided—one from Ace, the other from Rengoku—creating a towering vortex of fire.

The explosive firestorm engulfed the entire abandoned village, reducing it to ashes. In the blink of an eye, the battlefield was transformed into a scorched desert.

When the inferno settled, only three figures remained: Rengoku, Ace, and the unconscious Lt. Maharil.

Thud.

Ace watched as Rengoku gently laid Maharil on the ground.

"So you managed to rescue your subordinate in the middle of all that… Not bad. You move well."

"Huff—"

Just before the fire burst from his sword, Rengoku had ducked and grabbed Maharil, shielding him from the flames.

His Marine coat was now completely burned, and he bore light burns across his body—but the subordinate had been saved.

"As expected from a pirate with a 550 million bounty… but I can't afford to retreat now!"

Rengoku steadied his breathing and once again lowered his stance to charge.

"Flame Breathing, First Form—"

"Unknowing Fire!"

"Damn it, I've seen that move a few times now, but it's still such a pain in the ass to deal with!"

Rengoku's burst acceleration surpassed even the Soru technique of the Rokushiki.

Perhaps it was even twice as fast.

Because of that godspeed charge, Ace had to constantly keep his Observation Haki active. He knew he needed a way to bind Rengoku's legs somehow—or he'd be overwhelmed.

"Should've thought more about the versatility of my abilities…"

It was too late for regrets, but he realized now that he had no technique to restrain Rengoku's movement.

In the blink of an eye, the flame swordsman was at his side again—this time with a lower stance than before.

"Flame Breathing, Sixth Form—"

"Crimson Cross Sun!"

Recognizing the technique that had scarred his chest earlier, Ace immediately coated his upper body in Armament Haki to defend.

It drained a lot of Haki—but the technique's destructive power justified the cost.

Whoosh—whoosh!

"…Huh?"

Nothing happened.

Two feints.

Ace had been completely caught off guard.

"Damn it!"

Frustrated by the needless waste of Haki, Ace moved to counterattack.

But just as he adjusted his stance, a powerful blow struck his abdomen.

"Guhh!!"

"Fish-Man Karate: Tile Punch—Horizontal Strike!"

A devastating sideways punch landed directly in his midsection.

"Tekkai: Crash!"

Immediately following the Fish-Man Karate strike, a powerful blow empowered by Tekkai (Iron Body) from Rokushiki struck him again.

Those two lightning-fast attacks caught Ace in the moment just after he had dropped his Armament Haki defense. He couldn't react in time—he couldn't even transform into fire.

He hadn't expected it at all. He'd assumed Rengoku was purely a swordsman, but his martial arts were formidable.

Ace was flung backward, struggling to breathe as pain radiated from his stomach.

'Wait… not my abdomen—he aimed for the solar plexus...'

"Soru!"

Despite wielding a sword, Rengoku had used Soru instead of his usual charging technique to close the distance. Ace's mind began racing.

Was it just Soru? But he was fast—ridiculously fast.

Maybe using his usual charge too much strains his legs?

Is he going for punches now? Sword attacks? Or something else entirely?

Ace's thoughts tangled in confusion.

"Screw it! Whatever!"

"Fire Fist!"

Whatever Rengoku was planning, Ace decided to shut it down with a wide-area blast.

But Ace had made two critical miscalculations.

First—while Fire Fist was a wide-range technique, it moved in a straight line. Anyone who dodged up, down, or sideways could avoid it.

Second—his Logia-type flames could be cut.

"Black Blade – Logia Splitter!"

This time, Rengoku slashed not once—but four times, perhaps to protect the unconscious Maharil behind him.

His swift four-fold slashes sliced Ace's iconic flame attack—Fire Fist—into eight equal segments, like a pizza being evenly cut at a navy mess hall.

Then Rengoku reached Ace in a flash and drove his sword forward.

"Huff—"

"Water Breathing, Seventh Form!"

"Drop Ripple Thrust!"

Water Breathing.

A sword style with a nature completely opposite to Flame Breathing.

Rengoku knew this. In fact, switching suddenly from one breathing style to another could be reckless—even dangerous—to his body.

Especially when using Total Concentration Breathing, shifting styles mid-combat put severe strain on one's internal rhythm.

But luckily, he had begun transitioning his breathing pattern back during Crimson Cross Sun, and solidified the shift with the follow-up Fish-Man Karate and Rokushiki attacks.

All for this one strike.

Though Water Breathing was weaker in raw power compared to Flame Breathing, the black blade—imbued with Armament Haki—pierced through Ace's scapula, delivering a surge of relentless pain.

"As expected… my precision is still nowhere near Giyu's."

It wasn't a perfect hit—but Rengoku was satisfied.

Flame Breathing focused almost entirely on slashing techniques. It had no thrusting attacks.

But in order to capture Ace alive, Rengoku needed to immobilize him.

That's why he turned to Water Breathing, Seventh Form: Drop Ripple Thrust—a technique that could stop an opponent with a piercing blow.

His plan: stab Ace just enough to hinder his movements—then quickly apply sea prism stone handcuffs.

However, just as Rengoku reached to draw the cuffs—

Ace suddenly unleashed a silent surge of pure Conqueror's Haki.

Even though Rengoku was also a Conqueror's Haki user, the unpredictable burst caught him off guard.

"Guh—!"

With a roar, Ace took advantage of Rengoku's hesitation and forcibly yanked the sword from his shoulder. Blood sprayed as he leapt backward.

"Damn it… At this rate, one of us really might die..."

Enduring the pain, Ace pulled a small packet of powder from his pocket and poured it over the wound.

Whatever the substance was, it temporarily halted the bleeding from the deep puncture in his shoulder.

"Huff… Huff…"

There was no choice left. He would have to go all out.

"Damn… This wasn't meant for you, but..."

Ace spread his arms wide and assumed a stance.

In an instant, a massive circular flame sigil began to form around him.

It glowed like tree rings, concentric circles of tightly burning fire, incinerating everything in its radius—

—everything except in Rengoku's direction.

"Great Flame Ring!"

Seeing the enormous inferno rise around Ace, Rengoku narrowed his eyes and drew in a deep breath.

He shifted his posture, reigniting Flame Breathing within his core—and began rebalancing his stamina.

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