The three days leading up to the Captains' Meeting were thick with tension.
Yami drilled the Black Bulls with a ferocity that bordered on sadistic, pushing them past their limits. It was his way of preparing them for the fallout of what was to come.
Genos spent the time in his lab, a sealed-off room filled with the hum of his new core and the frantic scratching of a quill on parchment. He was designing something—new sensor arrays, defensive countermeasures—preparing for a battle he couldn't predict.
Saitama, for his part, did exactly what he always did. He read manga, watched clouds, and complained about the lack of sales at the local market. The impending duel with the nine most powerful mages in the country registered with the same emotional weight as deciding what to have for dinner.
But for Asta, the three days were a single, grueling, metaphysical lesson.
Yami took him to a secluded clearing deep in the forest near the base. Saitama was there too, sitting on a log, looking bored.
"Alright, kid," Yami began, lighting a cigarette. "The other day, when you scraped Baldy with your sword, you saw something. A limit. A seal. A cage. Whatever you want to call it."
Asta nodded, his grip tight on the Demon-Slayer Sword. "Yes, sir. Just for a second."
"I want you to see it again," Yami commanded. "But this time, I want you to feel it. Understand it. Find out how to touch it without breaking your arm, or the world."
Saitama sighed. "Are you sure about this? It feels like you're trying to figure out how to best poke a sleeping bear."
"You're not a bear," Yami grunted. "You're our problem. And we solve our problems by staring 'em in the face until they blink. Asta. Go."
Hesitantly, Asta approached Saitama. He wasn't attacking. This was different. He focused, letting the raw energy of his Anti-Magic grimoire flow into the blade, making the metal hum with a crimson-black aura.
He remembered the feeling from before—the utter, absolute wrongness of Saitama's non-presence. A human-shaped vacuum.
"Don't swing," Yami coached. "Just… touch him. The flat of the blade. Gently."
Asta took a deep breath and lightly pressed the sword against Saitama's shoulder.
The world dissolved.
He was no longer in a forest. He was floating in an infinite, silent void. Before him loomed the cage. It wasn't a metaphor. It was real, a construct of solidified, golden light, its bars woven from concepts he couldn't name—law, consequence, identity.
And inside it, contained but not tamed, was a storm. An ocean of incandescent power so vast it had its own gravity. It was a chaotic, beautiful, and utterly terrifying sight.
The hairline fracture he'd caused before was still there, a tiny imperfection on a flawless surface.
His sword was touching one of the bars. The Anti-Magic wasn't destroying it; it was resonating with it, acting like a tuning fork against a bell. Through the sword, he could feel the structure. He could feel the strain.
"What do you see, kid?" Yami's voice echoed from a world away.
"It's… real," Asta stammered, his consciousness struggling to describe the indescribable. "It's holding something back. Something… huge."
"Can you affect it?"
Asta focused. He tried to push, to channel more Anti-Magic. The golden bar he was touching groaned, not with the sound of bending metal, but like a law of physics being stretched to its breaking point. A single, blindingly bright thread of the power from within pulsed against the inside of the bar, and Asta felt a psychic backlash that threw him out of the vision.
He stumbled back, falling to one knee, the sword clattering to the ground. He was gasping for air, his head pounding. Saitama just stood there, completely unaffected.
"You okay? Your face is pale," Saitama observed.
"I felt it," Asta panted, looking at his shaking hands. "It's not a magic seal. It feels… natural. Like something he did to himself. Like a promise he made."
Yami took a long drag of his cigarette, his mind racing. A self-imposed limit. That was a concept he could understand. It was the core of all martial arts, of all magic control. But the scale of this…
"So," Yami mused, "what happens if you try to cut it?"
Asta looked up, horrified. "Cut it? Captain, I don't think I can! Just touching it felt like trying to punch a mountain."
"Not the whole thing," Yami clarified, walking over. "That crack you made. What if you focused all of your Anti-Magic, the sharpest point of your will, right on that tiny fault line?"
The implication was terrifying. What would happen if he widened the crack? Would the cage break? Would the storm get out?
Saitama, who had been listening with half an ear, suddenly spoke up. "You probably shouldn't do that."
Both Yami and Asta turned to him. His expression was still flat, but there was something in his voice. A sliver of something that might have been concern, or maybe just memory.
"The last time something messed with this thing… I got stronger. A lot stronger. But I also…" He trailed off, looking at his own hands as if he didn't quite recognize them. "...I lost something. Can't remember what it was."
The admission was so simple, so devoid of drama, that it was utterly chilling. The price of his power wasn't a grand, operatic sacrifice. It was a quiet, creeping amnesia of the soul. He wasn't just losing his hair; he was losing pieces of his own humanity with every broken limit.
Yami looked from Saitama's empty expression to Asta's terrified one. His plan had been to give Asta a trump card, a way to stun or disable Saitama if he went too far. Now he saw it was far more dangerous. Tampering with the cage wasn't a switch. It was a gamble with the man's soul.
He knelt down in front of Asta. "Listen to me, kid. The Wizard King wants a circus. So we're gonna give him one. But your job has changed. You're not going in there to stop him."
He met Asta's eyes, his own gaze deadly serious.
"You're going in there to make sure nobody, not Fuegoleon, not Nozel, not even Julius himself, lays a single goddamn finger on that cage. Protect the limit. No matter what."