Lifesaving medicine or poison

Morning at the Butterfly Mansion Estate should have been peaceful.

The Sapphire Star lay sprawled on her soft bed, smacking her lips, seemingly still savoring last night's sweet, tender Sakura Mochi with its faint cherry-blossom fragrance in her dreams-the Butterfly Mansion Estate's sweets really were better than headquarters'.

"Snore... snore..." Soft snores echoed through the room.

Hmm? The smell of blood...

Half asleep, the Sapphire Star caught a whiff of blood.

BANG!!!

With a tremendous crash, the door burst open!

"Lady Sapphire Star!!!"

Hikigusa's voice, so frantic it cracked, pierced her peaceful dream like an icicle.

The Sapphire Star was no longer half asleep. She shot upright, her right hand instinctively reaching for the Fatalis Demolisher's hilt beside her pillow.

"Shit?! Is Muzan attacking?!"

Her eyes were bleary, her golden pupils still holding the confusion of being jolted awake alongside a sudden burst of vigilance. Her voice was hoarse with sleep.

Hikigusa braced against the doorframe, chest heaving, face filled with unprecedented urgency.

"No, that's not it! It's Lord Kyojuro Rengoku! He... he encountered Lower Rank One and Upper Rank Three! He's critically wounded, barely alive! The Kakushi risked their lives to bring him back! Please bring your best medicine! You're the only one who can save him now!"

"Rengoku?! That owl guy?!"

The Sapphire Star's mind rang.

That Flame Hashira who was as lively as a blazing fire, with that booming voice, who'd even treated me to a meal?! Dying?!

What? Am I still asleep? Didn't they only leave yesterday afternoon?

Didn't those three kids go with him? Didn't I give every Hashira an Ancient Potion?

With no time to put on her outer armor, the Sapphire Star wore only her thin hunter's underlayer as one hand darted into the hunter's pouch at her waist, unerringly grabbing several small leather bags and medicine bottles of different colors.

She moved so fast she left only an afterimage behind, already charging out the door!

Hikigusa felt a gale sweep past and hurriedly turned to follow.

The Sapphire Star needed no directions-

The pungent stench in the air, a mixture of scorching, blood, and ruptured organs, led straight to the Butterfly Mansion Estate's infirmary like a thread of despair!

"I shouldn't have stayed up so late! That smell was so obvious, and I didn't even wake up. I'm fucking useless!"

BANG!

The Sapphire Star brutally shouldered open the infirmary door!

The sight before her made her heart sink.

Kyojuro Rengoku's large frame lay on a makeshift stretcher. His golden-red hair, usually like a blazing fire, was dull now, caked with blood and dirt.

His signature flame-patterned haori was in tatters, soaked in blood so dark it was nearly black, clinging to a horrific wound that had almost pierced his entire torso!

Several young nurses from the Butterfly Mansion Estate were frantically trying to stop the bleeding and clean the wound, but their efforts were a drop in the bucket against injuries this severe.

Tanjiro, Zenitsu, and Inosuke knelt beside the stretcher, covered in wounds, their faces smeared with tears, blood, and unbearable grief.

Tanjiro bit his lip so hard it bled; Zenitsu was crying himself almost breathless; even the usually wild Inosuke looked utterly drained. His Boar Headgear hung askew, exposing a face covered in tear tracks and scrapes, his eyes hollow.

"Lady Sapphire Star!" Seeing her rush in, Tanjiro clung to her like his last lifeline, his voice hoarse and broken. "Please! Save Rengoku!"

The Sapphire Star wasted no words, stepping straight up to the stretcher.

"Move aside! If you're not injured, don't touch my Lifepowder!"

The nurses instinctively stepped back.

The Sapphire Star drew a deep breath and flicked her wrist, sending a small leather pouch filled with powder that shimmered with strange starlight high into the air!

"Might Lifepowder! Go!"

WHOOSH!

First, she restored some of the injured man's stamina.

"Great Sushifish Scale Lifepowder!"

Next came a cloud of emerald powder like a miniature galaxy, precisely enveloping Kyojuro Rengoku's entire upper body!

The instant the powder touched his wounds, it gave off a faint sizzling sound. The curled, charred edges of flesh visibly began to writhe and draw together!

Miraculously, the torrent of blood slowed!

But that wasn't enough. The humans of this world didn't have hunters' absurd constitutions.

"Max Potion! Swallow it!"

As the Max Potion entered his mouth, Rengoku's heartbeat, so faint it had almost stopped, suddenly surged.

Like a sleeping volcano forcibly awakened, searing vitality erupted from the deepest reaches of his body!

An unnatural flush instantly spread across his paper-white face, yet it was a flush that signaled life!

Under the combined effects of the Lifepowder and Max Potion, muscle tissue around the terrible wound through his chest grew, intertwined, and healed at a frantic, visible pace! Though he was still far from fully recovered, the deadly ebbing of his life had been forcibly halted!

"Ugh... cough!" Kyojuro Rengoku suddenly coughed up a great mouthful of black blood containing fragments of his organs. Then his chest began rising and falling with unmistakable strength! Though still weak, his breathing finally steadied! He was out of immediate danger!

"Rengoku!!" "Mr. Rengoku!!" The three boys burst into relieved cries and crowded beside the stretcher. Seeing his breathing return and color fill his face, they babbled incoherently, tears pouring out with their joy.

"He's... he's alive!" "Thank goodness! Waaaah... Lady Sapphire Star! Thank you! Thank you!" Zenitsu clung to Rengoku's uninjured arm, sobbing like a child.

Tears streamed down Tanjiro's face too as he bowed deeply before the Sapphire Star. "Lady Sapphire Star! Thank you! I'll never forget this as long as I live! Waaaah!"

Only then did the Sapphire Star's taut nerves ease a little, and she let out a long breath.

"This shouldn't have happened..." she murmured, her gaze passing over the massive wound on Rengoku's body, no longer fatal but still gruesome.

"Didn't I give every Hashira an Ancient Potion to save their lives? As long as you've got a breath left, that stuff brings you straight back to full health. It even mends broken bones! How did he get this badly hurt?! Did he not take it?!" The Sapphire Star looked questioningly at the sobbing Tanjiro.

The question stunned Tanjiro, then deeper anguish and grief crossed his face. He wiped his tears forcefully and explained through his sobs.

"He... he did! Lady Sapphire Star! After we... we killed Lower Rank One, Upper Rank Three, Akaza, suddenly appeared! He was too strong! Rengoku fought with everything he had to protect everyone on the train and us, but he still... he still wounded him terribly! He punched through his chest... By then, Rengoku was already... already almost gone!"

The resolute look and words Rengoku had given them as he lay dying flashed through Tanjiro's mind.

"Just when we thought... thought he was going to..." He choked up, unable to continue, and took a deep breath before going on. "Rengoku... swallowed the medicine you gave him without hesitating! Then... then..."

Time turned back to that night.

Kyojuro Rengoku's powerful body slammed heavily onto the twisted tracks. A huge bloody hole pierced his chest from front to back, blood gushing like a burst dam and staining the gravel beneath him red.

The flames in his golden-red eyes had dimmed to almost nothing. Every breath carried bloody foam and fragments of his organs; his life was a candle flickering in the wind, ready to go out at any moment.

Akaza stood a short distance away, a trace of admiration in his eyes overshadowed by condescending indifference.

"Kyojuro! Your resolve is admirable, but this is the limit of humanity! Become a demon, and pursue eternal martial mastery with me!"

"Cough... heh..." Rengoku coughed up a great mouthful of blood, yet his face pulled into an almost wild smile. His blood-soaked hand trembled, but reached with extraordinary resolve for the little pill at his waist that the Sapphire Star had given him.

"Eternity...? Heh..." He abruptly shoved the pill radiating astonishing life energy-the Ancient Potion-into his mouth and swallowed hard!

"RAAAAH!!!"

A roar brimming with immense vitality exploded from deep in Rengoku's throat!

A visible wave of crimson air burst outward from Rengoku! His dim golden-red eyes reignited with flames fiercer than they had been at his peak! Vast fighting spirit surged around him like magma!

He sprang to his feet, his torn haori snapping in the scorching gusts, his whole being like a war god's furnace reborn in fire!

"Akaza!!!" Rengoku's voice thundered, carrying a resolve to burn everything to ash.

"Come again! This time, I will cut you down here! This is the 'blessing' that warrior from another land bestowed upon me! My flames have not yet burned out!"

Akaza's composure vanished instantly. "Wh... what?! Impossible! Just now, you were clearly..." He stared at the wound in Rengoku's chest, healing at incredible speed and even emanating a stronger presence, and at his vitality erupting like a volcano.

"What did you take?! How could a human have something like..."

"Enough talk!" Rengoku gave him no time to think, driving Flame Breathing to its utmost. "Flame Breathing: Ninth Form: Purgatory!!!"

Scarlet flames towered skyward! With power enough to burn cities and destroy the world, a flaming blade aura fiercer and more concentrated than before tore through the predawn darkness and slashed savagely toward Akaza!

That strike held all his strength and resolve, surpassing his own peak!

At last, gravity appeared in Akaza's eyes, and even a hint of... excitement.

He stopped holding back, his warrior's soul fully ignited.

"Interesting! So interesting! To think a human could reach such heights! Then let me see how far this borrowed power can burn! Destructive Death: Annihilation Style!"

Dark-red blasts from his fists collided once again with city-burning flames!

This time, the shock wave sent every remaining fragment of the train flying!

Rengoku's blade actually suppressed Akaza's punches for a moment! It even left several charred, bone-deep cuts in his demonic body, harder than fine steel!

"Ugh!" Akaza grunted, the shock in his eyes deepening.

This strength... this recovery... it defies all reason!

"Hahahaha! Excellent! Again!" Rengoku laughed wildly, his blade unleashing an unbroken onslaught, every strike carrying the savage resolve to perish together!

The Ancient Potion had done more than restore his body. It had briefly driven his spirit, his will, and even his very life force to burn at their utmost! He felt stronger than ever, as though he could cut through anything before him!

Yet Akaza was still Upper Rank Three! Once the initial shock passed, his battle instincts as a supreme martial artist and the advantage of his undying demon body began to show.

How could a Max Potion's healing compare with a demon's endless regeneration?

"Hmph! Borrowed fire is nothing but an illusion in the end!" Akaza saw through Rengoku's condition, and his attacks grew fiercer and more insidious!

Using his ghostlike speed and inhuman reflexes, he pressed into close combat, targeting the gaps between Rengoku's attacks and the weak points in his defense!

BANG! CRACK!

A cunning blast from his fist smashed into Rengoku's sword wrist! The sound of shattering bone rang out clearly!

RIP!

Another blast grazed beneath his ribs, tearing away a swath of scorched flesh!

Inevitably, Rengoku's movements faltered slightly.

Though his injuries healed rapidly under the Max Potion's effects, each recovery ravenously consumed his already overdrawn vitality, bringing deeper exhaustion and a burning pain that reached his very soul.

"Do you see now, Kyojuro Rengoku?!" Akaza's voice dripped with cold mockery. "Your strength is fading! Your flames are dying! But I have unlimited time! Unlimited chances! What can you possibly use to destroy me?!!"

On the horizon, the first golden ray of dawn pierced the thick clouds.

Absorbed in battle, Akaza had failed to notice dawn approaching, and sunlight sizzled against his skin.

"Damn it!!" Feeling the burning pain of sunlight, Akaza roared in frustration.

He took a long look at Kyojuro Rengoku, battered and beginning to breathe unsteadily, yet with eyes still burning with unyielding flames, and at the strange vitality within him that was rapidly ebbing but still made his heart tremble.

Unacceptable! Utterly unacceptable! I've never had such an exhilarating fight, never seen a swordsman who could heal his wounds!

All because of that damned sunrise, I can't keep fighting.

After today, will I ever meet another warrior this fiercely desperate?

"What you took... what exactly was it? Did that warrior from another land give it to you...? Hmph! I'll remember this!"

Before his words had faded, Akaza's figure slipped like a phantom into the shadows and vanished instantly.

He left behind only wreckage and... Kyojuro Rengoku, leaning on his sword, drenched in blood, his body swaying slightly, but his back still ramrod straight.

The Ancient Potion's effects receded within him like the tide. The forcibly kindled fire of his life instantly dimmed, and crushing exhaustion and even graver injuries came crashing back like a landslide and tsunami! His vision went black. Unable to hold himself up any longer, his powerful frame toppled with a thunderous crash!

The scene returned to the Butterfly Mansion Estate's infirmary.

"...Then Rengoku..." Tanjiro's voice held endless grief and lingering fear.

"Rengoku... to seize that tiny chance to kill an Upper Rank, he used every bit of strength the Max Potion gave him... But... but..." He could say no more, and tears welled up again.

The Sapphire Star listened silently, her expression slowly freezing.

She looked at Kyojuro Rengoku on the stretcher, his breathing still faint, an unhealthy flush on his face...

Slowly, she lowered her head and looked at the hand that had just scattered Great Sushifish Scale Lifepowder and fed him a Max Potion. Her fingertips seemed to retain the scorching touch of Rengoku's skin-the heat caused by the Max Potion forcibly burning his life.

It was me... that Ancient Potion I gave him...

If I hadn't given him that medicine... he would have lost consciousness, but at least...

At least he wouldn't have had his life forcibly ignited by the Max Potion, only to fight an even more brutal battle he knew he had little hope of winning?

Would he... have been spared this double dose of suffering and exhaustion?

Did I... give him "hope," only to drive him to fight until he shattered himself?

For the first time, cracks of bewilderment and self-doubt appeared in the Sapphire Star.

The medicines she took such pride in, the Ancient Potion she treasured for its power to bring people back from death... in this world, in the hands of a warrior like Kyojuro Rengoku who valued duty and conviction above his own life, had it... become a double-edged sword?

A... poisoned blade that tempted its wielder to burn himself out and charge into an even more hopeless abyss?

Back home, Max Potions were a hunter's last trump card for challenging Elder Dragons and surviving desperate situations. Everyone valued their lives. They took medicine to survive, to make it to the next hunt.

No one... took medicine like Rengoku, just to charge in and perish together with an even more terrifying monster!

"Lone Bird... Blaze... Master... if you knew the medicine I gave someone made him fight this recklessly... would you call me an idiot?"