Based on his knowledge of the manga, Gusion knew that fighting powerful demons required three major factor used by the Pillars: the Transparent World, Demon Slayer Marks, and the Bright Red Nichirin Blade.
He understood the Transparent World as a special state that lets you see through an enemy's body—muscle tension, breathing rate—to predict their moves. It's essentially a powerful ability to see through opponents.
Demon Slayer Marks are a potential-unlocking state for the human body, but overexertion shortens the user's life, and those who awaken Marks rarely live past 25.
As for the Red Blade, originally only users of Sun Breathing could infuse their blade with power to superheat it, making it more deadly to demons.
Later in the manga, the Pillars could also turn their blades red by gripping them tightly or clashing them together, raising the temperature.
Honestly, Gusion wasn't interested in these techniques.
He already had a skill for unleashing potential and boosting strength. Such berserk skills can't be used infinitely, or explorers would just learn those and never improve their base stats.
As for the Transparent World, the key to hiding one's own aura was useful, but reading opponents and predicting their moves or flow of power—Gusion could already do that, so he didn't need a see-through skills.
In life-and-death combat, Gusion mostly relied on his combat intuition.
The last ability—the Red Blade—was even more useless to him.
What mattered most from this world, he'd already obtained: breathing techniques.
He'd always been interested in internal energy breathing methods; these were the real game-changers, providing stat boosts.
Without high base stats, abilities like Transparent World, Marks, or the Red Blade are useless. The Mist Pillar's attacks after Marks can't compare to Yoriichi's.
It's not that the ancestors were innately superior; it's that their stats were on another level.
In the manga, when the Stone Pillar awakened his Mark, it was different—he landed critical hit after critical hit, putting the Upper Moon One under real pressure.
So Gusion felt there was no need to study all the fancy abilities in this world—just master the breathing techniques.
With Total Concentration Breathing, breathing methods could permanently improve someone's physique. That's why Gusion categorized them as internal energy.
In battle, using full-power breathing techniques could further boost one's stats—both a long-term and an explosive benefit.
Breathing techniques were a good early system for explorers. Gusion figured they'd be effective up through the first or second tier.
If he could fully grasp and improve the breathing techniques, he might get even more stats and use them longer.
For now, he felt that breathing techniques were easy to learn but hard to master. At least, his current stats hadn't improved yet; only when using Thunder Breathing did his stats spike a bit.
Of course, Thunder Breathing's key feature was godspeed.
When using it at full power, he gained a significant speed boost, making his Shunpo even faster.
Greater speed meant his Mazuko sword did more damage, so the benefits of breathing techniques weren't just about numbers—the unique features of each style were vital.
"In this Mount Fujikasanen, there are demons captured alive by swordsmen. But the demons cannot escape…"
A crisp female voice interrupted Gusion's thoughts as he looked up to see two short-haired twin girls emerge from the wisteria forest.
They wore kimonos with wisteria patterns and had violet onion-like eyes, which looked a bit eerie at first glance.
Seeing the girls, Zenitsu instinctively moved closer behind Gusion, trembling.
The white-haired girl began explaining the selection rules. "Because wisteria blooms all year round up to the mountainside, which demons hate. Beyond that, there are no more wisteria, so demons roam there."
Hearing this, Zenitsu shivered and shrank closer to Gusion. He knew the selection's details already, but couldn't help being scared.
"Survive for seven days inside. That's the qualification for passing the Final Selection."
The black-haired girl continued.
Many Demon Slayer candidates exchanged nervous glances, though some looked calm. Gusion glanced around and, besides the main cast from the original story, spotted two older participants—likely explorers.
The two explorers also noticed Gusion, and their surprise flashed before turning grim.
Those two were in a terrible mood, having realized upon arrival that there were hardly any Demon Slayer faction explorers here.
Out of the 36 explorers who entered this world, if only those at the selection were on the Demon Slayer side, then… they'd be outnumbered roughly 3 to 33!
Plus, the Muzan faction already had a combat advantage—what was the point anymore?
The two exchanged glances, both feeling hopeless and already planning to hide out and survive if there were no mandatory elimination missions.
"Now, please proceed safely."
The kimono-clad twins bowed and offered good wishes.
This only annoyed the explorers more. They weren't scared of the selection, but those words—proceed safely—felt like a death sentence for their future in this world.
"Gusion-senpai, I'm scared, but I'll try not to hold you back."
Zenitsu forced himself to speak, suppressing his fear. He knew Gusion would protect him, but since he was here, he didn't want to be a useless burden and let his grandfather down.
Gusion smiled, surprised Zenitsu wasn't clinging to him. "Let's make a deal: If you slay one demon, I'll guarantee your safe passage through the selection."
"Just one demon?"
Zenitsu froze. "But… demons are scary…"
He lowered his head, realizing his own cowardice. There were probably countless demons on the mountain. Gusion had only given him the simplest trial.
"I understand, Gusion-senpai. I'll do my best to slay a demon!"
Zenitsu mustered his courage. He realized that if he couldn't even kill one, he wasn't fit to be a Demon Slayer. Even if Gusion helped him pass, he'd only fall into greater danger later—Gusion couldn't watch over him forever.
Did he really want to be called a useless coward? He didn't want to worry his senpai or disappoint his grandpa. So he'd try to slay a demon and become a qualified Demon Slayer.
Gusion saw the others enter the mountain and started forward. "Let's go. Time to begin our selection."