The demon drug — in the Monster Hunter world — is a potion that boosts a Hunter attack power.
But in Sherwin inherited memory, its true effect was to enhance strength and speed, essentially a weaker version of demon mode.
The one Haibara Meow made had a similar effect to the original: increased power, but with the same drawback as demon mode — it consumed stamina faster.
And unlike in the game, it didn't last until the Hunter fainted. Still, compared to the benefits it brought, that minor side effect was more than worth it.
As for how the demon drug was developed…
Back when Klee Meow went treasure hunting in the Alabasta Kingdom, she accidentally blasted open three bottles of an unknown potion — which turned out to be the "Hero Water" once drunk by the Birdclaw Squad in the manga.
Haibara Meow didn't like the original Hero Water fatal aftereffect — where drinking it meant certain death — but she did find inspiration for developing the demon drug from it.
By greatly reducing the negative effects while retaining most of the strength boost and even extending its duration, she perfected the formula.
On top of that, Haibara Meow also integrated the lethal properties of Hero Water into her poison gas bombs.
The watermelon-like stripes that appeared on those attackers earlier were derived from the external symptoms caused by Hero Water.
"Click click click… huh?"
Sherwin swallowed the demon drug with a grimace, then smacked his lips in surprise, glancing at Haibara Meow.
Unlike the prototype, this version wasn't bitter or unpleasant — instead, it had a refreshing watermelon juice flavor that Sherwin actually liked.
"Hmph~"
(=｀3=)
The little tsundere kitten puffed up her cheeks and turned her head away.
"You don't seriously think that drinking some weird potion means you can beat me, do you?"
Sensing the change in Sherwin aura through Observation Haki, Rayleigh furrowed his brow deeply.
As an old-school pirate who never relied on Devil Fruits, he'd always looked down on those who sought external power boosts.
He'd thought Sherwin had some backbone, but now, Rayleigh impression of him instantly plummeted — even lower than before.
Sherwin didn't think there was anything wrong with it. Whether in the game or in his inherited memories, there were plenty of Hunters who relied on items and potions — in fact, in those memories, that type of Hunter made up the majority.
After all, reality wasn't a game. When facing monsters whose size and power far surpassed their own, no Hunter would hesitate over whether their methods were "proper" or not.
"How would I know if I don't try?"
Without bothering to explain further, Sherwin drew the Longsword from his back and slashed straight toward Rayleigh.
Monster Hunter Style — Crimson Meteor!
"Oh?"
Rayleigh, who had thought Sherwin was only relying on drugs, was surprised again.
Sherwin strength and speed weren't bad at all, and the Armament Haki he displayed was exceptional for someone his age.
Strength and speed could indeed be boosted by potions, but Haki — that was real.
Rayleigh didn't believe there was any kind of potion that could enhance a person Haki level.
"Interesting."
Amused and intrigued, Rayleigh didn't dodge. He extended his pitch-black right hand, his five fingers like iron clamps, and caught the Longsword with precision.
At first, Rayleigh had intended to block Sherwin strike with one hand to show his superiority.
But he hadn't expected that Sherwin — empowered by the demon drug and his activated demon mode — would possess physical strength nearly equal to his own.
As a result, Rayleigh one-handed block turned out to be a bit reckless his five fingers gripping the Longsword trembled as if they might lose their hold.
However, Rayleigh combat experience was unmatched. In an instant, he adjusted — he swung the Longsword aside with a sharp flick of his right hand while stepping slightly to his left, letting the blade graze past his shoulder.
Then, taking a small step back to widen the distance between them, he tucked his right hand behind his back and discreetly flexed his fingers.
"Not bad… looks like I underestimated you a little."
Though Rayleigh had just suffered a minor setback, his expression remained calm and collected, as if nothing had happened.
Sherwin didn't bother replying. His body twisted sharply as he swung the Longsword in a powerful spinning arc aimed at Rayleigh flank.
Monster Hunter Style — Windfang Tornado!
Not expecting Sherwin to be so relentless, Rayleigh quickly bent backward in a deep motion that seemed almost impossible for someone his age, narrowly dodging the sweeping blade.
Then, in one smooth motion, he followed up with a Capoeira-like kick aimed at Sherwin neck.
Monster Hunter Style — Longsword — Backstep Slash!
While dodging Rayleigh strike, Sherwin used the Longsword superior reach to counter, slashing backward at Rayleigh arm that was supporting him on the ground.
But Rayleigh reacted instantly. He pressed his palm to the ground and used it to launch himself backward — a reversed version of a small evasive leap — escaping Sherwin attack range.
"Your Observation Haki not bad either," Rayleigh said sincerely as he straightened up. "Seems I'll have to start getting serious."
The moment his words fell, Sherwin suddenly couldn't hear Rayleigh "voice," couldn't see his "color," and even the presence he sensed before became faint and obscure.
Observation Nullification?
Sherwin narrowed his eyes, recalling Oda latest note about Shanks — it described an ability that used Conqueror Haki to stabilize one aura, preventing Observation Haki users from foreseeing their movements.
Considering that Rayleigh had once sailed on the same ship as Shanks — and might've even taught him this technique — it made perfect sense that he could use it too.
Before Sherwin could come up with an effective counter, Rayleigh had already closed the distance, lunging toward him.
Unable to track his movements with Observation Haki, Sherwin had no choice but to focus all his attention on Rayleigh every motion.
"Hu—!"
Rayleigh right fist cut through the air with a fierce whoosh, slamming toward Sherwin shoulder.
Sherwin quickly raised his blade to block—but that strike was merely a feint. Rayleigh hidden left hand suddenly shot forward, fingers pressed together like a viper flicking its tongue, stabbing toward Sherwin wide-open right flank.
Although Sherwin hadn't foreseen Rayleigh move, he wasn't completely unable to react. But being able to react didn't mean he could respond in time.
So…
Link Time! Activate!
Under Rayleigh astonished gaze, Sherwin—who should have had no way to block that strike—suddenly burst forth with unbelievable speed. Not only did he twist aside to dodge the stabbing hand, he even lunged forward and slammed hard into Rayleigh chest.
Monster Hunter Style · Great Sword · Shoulder Charge!
Even though Rayleigh had sensed Sherwin next move through Observation Haki, Sherwin speed during Link Time was so fast that Rayleigh had no chance to respond.
He was struck dead center and sent flying backward by the powerful impact.
Sherwin, unwilling to relent after gaining the advantage, stomped forward and chased after him.
During the pursuit, he swiftly drew the Longsword to his waist, taking the stance for Iai Slash.
After all, Link Time only lasted for a short duration, and activating it repeatedly in a brief span placed tremendous strain on the body.
He had to make the most of it while the effect was still active—deal as much damage as possible before it ended.
As the effect of Link Time was about to fade, Sherwin, already brimming with energy, swung the Longsword in a perfect arc that tore through the air and struck fiercely at Rayleigh, who was still midair…
Monster Hunter Style · Secret Art · Crimson Heaven End!