Butterfly Estate, a certain patient room—
"Big monk, are you the one Sister Kanae said saved her and Shinobu when they were little?"
The man was towering and imposing. Just standing there made it hard to breathe.
Kanae and Nezuko both looked up at Gyomei Himejima.
"Mitsuri! How could you address Brother Himejima like that!"
Kanae Kocho was clearly very respectful toward Gyomei Himejima. After all, he was her childhood savior—and not to mention, the strongest Hashira of them all.
"It's fine, Kanae. It's just a nickname."
"But you're alright now. That's all that matters."
The white, pupil-less eyes of Gyomei once again overflowed with tears. As the strongest among the Nine Hashira, he was always extremely busy. But he had always regarded the Butterfly Sisters as juniors he deeply cared about. If possible, he hoped they could live peacefully for the rest of their lives.
After receiving a letter from Lord Ubuyashiki saying Kanae had been seriously injured, he rushed back immediately. Now that he saw her alive and full of spirit, his heart was finally at ease.
"This time, it's all thanks to Yohan."
Gyomei had already been briefed on the entire incident. Who would've thought the next time he'd hear Yohan's name after that Hashira meeting, it would be in the context of slaying Upper Moon Two?
Too much had changed.
"By the way, where is Yohan now?"
Gyomei didn't see Yohan in the room. He had planned to personally thank the man face-to-face.
"You'll have to ask Mitsuri," Kanae said with a chuckle. "She probably knows."
"Hehe, Sister Kanae~ Yohan went to the back mountain. Said he was testing something."
"Is that so?" Kanae was a little curious about what Yohan was up to, but with Gyomei present, it wasn't easy to ask further.
"Right! He said after defeating Doma, he had some kind of insight and left to try something."
" Yohan is truly diligent," Gyomei said with admiration.
Elsewhere—behind the Butterfly Estate
"System, why'd you make me come all the way out to the back mountain just to claim a reward this time?"
In the past, he could claim rewards anywhere. This time, however, the system insisted he find a secluded place.
[Ding! This reward is highly special and requires a large open space.]
[Random Mission: Fate of the Butterfly (Completed)]
[Mission Reward: Demon bound Armor (Advanced)]
[Host, once location is confirmed, advancement can begin]
This reward had been triggered during Yohan's battle with Doma, but at the time he had no bandwidth to check it. All he was focused on was how to smash Doma into oblivion.
Now that he was back and Kanae was safe, he could finally indulge in the prize he had been so eager for.
He looked around.
This was the forested back mountain of the Butterfly Estate. Due to its remote location, the Demon Slayer Corps' HQ and the Estate were surrounded by wilderness. There was no one here.
Perfect. "Alright, system, let's start." Yohan confirmed.
[Demon bound Armor—Advancement Initiated!]
The blade in Yohan's hand instantly burst into a radiant red glow. Faintly, he could even hear a dragon's roar.
The crimson light faded.
Yohan immediately noticed that the blade felt far more agile in his hand. The red gem embedded in the hilt… had it just moved? It looked like an eye, rotating.
"…So this is it?"
He couldn't help but complain. Did he really need to trek all the way out here just for this? Couldn't he have done this in his room?
[Please use Demon bound Armor!]
[Please use Demon bound Armor!]
Even the system's mechanical voice sounded unusually excited.
Thinking for a moment, Yohan planted the sword into the ground in front of him.
Demon bound Armor—Activate!
Blinding golden light surged through the mountains. The malevolent spirit reappeared, hovering behind Yohan.
He felt the change instantly. Previously, activating Demon bound Armor brought no sensation at all. But now—his mind ached, like a spike had been driven through his skull.
"System, what the hell is going on?!"
[Host, please don't panic.]
[Demon bound Armor is an imperial weapon forged from the dangerous beast 'Tyrant'. It possesses limitless evolution potential.]
[The system has just upgraded it for you. After the evolution, it now places immense strain on the user's mental capacity.]
"Wait, wait—didn't you say all system products were green-coded, safe, and reliable?!"
"Are you scamming me?!"
[The mental pain will only happen once. Afterward, your mental power will skyrocket.]
"…So now my physical strength is maxed, and my mind is buffed too?"
"Not bad. Not bad at all."
Yohan was satisfied. Up until now, all his enhancements had been physical. He had always wondered if he'd be vulnerable to mental-type Blood Demon Arts.
But now, with his mental resilience enhanced to the point he could withstand even dragon-level pressure, what Blood Demon Art could possibly faze him?
Just then, Yohan noticed something odd.
He… wasn't on the ground anymore.
Wait—am I flying?!
He looked down.
The armor covering him had turned entirely golden. Under the sunlight, he looked like a celestial dragon descending to Earth.
"Wings?"
Only now did he realize why he hadn't fallen. The armor had wings—real ones. And they moved perfectly with his will.
His first flight—it was so exhilarating he couldn't stop. He soared through the forest like a golden blur, zipping between trees.
"This is amazing!"
The first human capable of true flight—Yohan never wanted to come down again.
But the power in his body… it needed release, screaming for it.
He flew straight toward a massive boulder and threw a punch.
BOOM!
The boulder didn't break.
Surprised, he thought maybe he hadn't hit it hard enough and prepared for another strike.
Then, like watching slow motion—
Cracks spiderwebbed across the rock's surface.
CRACK!
The entire boulder disintegrated into powder. Gone, as if it had never existed.
"…Wait, what?"
Yohan knew exactly how strong he was. Previously, a full-force punch might shatter a rock, sure.
But this? He barely even touched it.
It still crumbled.
Dragon's strength.
Now he understood why the system had demanded solitude. If that had happened at the Estate, the entire building would be rubble by now.
Still awestruck by his newfound might—
" Yohan, truly admirable."
Gyomei Himejima had rushed over after hearing Yohan was at the back mountain. His previous opinion of Yohan had been lukewarm—strong, sure, but nothing more.
But after hearing how he saved Kanae and killed Upper Moon Two?
Gyomei had a complete change of heart. He had to thank the man personally.
Originally, he had just reached the foot of the mountain when the ground suddenly trembled violently, like an earthquake. He hurried up, only to witness—
Destruction everywhere.
Trees flattened as if by a hurricane. Boulders shattered. Craters in the ground, as though a great battle had taken place.
"I…" Yohan opened his mouth, ready to explain.
"No need to say anything, Yohan. That you wield such strength yet continue to train so diligently—I deeply admire you!"
….