Raiden's progress remained stuck at ninety eight percent. Even after mastering four additional Breathing Forms, his strength had only improved by two percent.
He did not believe Tamayo's remaining Blood Demon Art would be enough to close that gap.
Strengthening his bond with the Hashira was not something he could accomplish quickly, so the only path left was to rely on himself.
Raiden sat cross-legged, closed his eyes, and took a slow breath. He began to regulate his breathing carefully, focusing on the flow of air through his body.
He concentrated on every movement of his breath, guiding it steadily from his lungs to the rest of his body. Normally, this would create a faint but clear sense of growth, a subtle increase in power that he could feel deep inside.
Today, it was completely different.
The breath flowed just as before, but there was no response. No warmth, no pressure, no familiar surge of strength. It felt as if everything inside him had gone silent.
With every breath, he felt nothing but calm, like standing in the middle of a still lake where not even a ripple existed.
Raiden frowned slightly and increased the rhythm of his breathing, hoping the faster pace would break the deadlock.
Nothing changed.
He adjusted the pattern again, forcing more power into each breath, trying to draw out even the slightest reaction from his body. It was useless. Every attempt ended the same way, quiet and unmoving.
Time passed slowly. Sweat formed on his forehead, and his muscles began to ache from the strain of forcing his breathing beyond its natural rhythm. Still, he refused to stop.
At last, he opened his eyes.
A faint, bitter smile appeared on his face.
"At this rate, it will take at least half a month to break through," he muttered.
That was only an estimate. If the difficulty increased again once he reached ninety nine percent, it could take even longer.
He had clearly reached a bottleneck. Simply practicing his Breathing Style was no longer enough.
Raiden stood up and stretched, feeling the stiffness in his shoulders and the soreness in his arms. He looked toward the distant sky, a quiet sense of frustration rising inside him.
Even without breaking through, he believed he could hold Muzan back for a while. The problem was the cost.
If he fought like that, he could not guarantee the safety of the other Hashira.
Raiden was not someone who would sacrifice himself for strangers without hesitation. At the beginning, he had only grown close to the members of the Demon Slayer Corps because of the system that tied them together.
But things had changed.
Even if his reasons were selfish at first, he now genuinely saw them as friends. Uzui Tengen and Shinazugawa could be exhausting to deal with, but that did not mean he disliked them.
The outcome he wanted most was simple. Everyone would survive, except Kagaya.
But that was only possible if he broke through.
Without that final step, even Raiden was not completely confident he could defeat Muzan.
"Forget it. I will do everything I can," he said quietly.
Right now, the only thing he could do was grow stronger before Muzan arrived.
"Do you want to fuse the Blood Demon Art, Bewitching Blood and Day's Demonic Scent, now?"
"Yes."
The moment the fusion began, a strange aura surged through his body.
It felt completely different from the power created by Breathing Styles. This energy was colder, quieter, and far more mysterious.
The power moved slowly through him, spreading from his chest to the rest of his body. It felt like something ancient was being carved into his very existence.
The sensation was uncomfortable at first, but Raiden quickly adapted.
His consciousness seemed to drift into a hazy dream. Everything around him blurred, as if he were walking through a world covered in white mist. He could not tell what was real and what was not.
His body felt light, almost weightless, like it could disappear into the air at any moment.
When the fusion finally ended, the power settled deep inside him and spread quietly through his entire body.
It tried to push him past the barrier.
But it was not enough.
The force only created a faint ripple before fading away.
Raiden was not surprised.
Even the Breathing Forms of the Hashira had not been enough. There was no reason Tamayo's Blood Demon Art would succeed where they had failed.
Still, it helped him improve slightly, and that was enough for now.
He stretched again and exhaled slowly. From this point on, everything depended on his own training.
…
The next morning, Raiden woke up early and opened his door.
A Kasugai Crow was perched on the courtyard wall, carefully preening its feathers. It was wearing a small scarf, and the moment it saw Raiden, it stopped moving and nodded politely.
"Sound Pillar. Master requests your presence."
Raiden nodded. Something about the message felt different today.
He quickly got ready and followed the crow toward the Ubuyashiki residence.
Sunlight filled the old courtyard, lighting up the moss-covered stone steps and the vines climbing along the walls. It looked peaceful, but Raiden felt a heavy sense of unease growing inside him.
By the time he reached the entrance, that feeling had already turned into dread.
He pushed the wooden door open.
A strong smell of decay hit him immediately.
Raiden frowned. The smell was so heavy that it made his chest tighten.
Has Kagaya's condition already reached this point?
The thought alone made him uneasy, but he did not hesitate. He stepped inside and walked deeper into the courtyard.
It was completely silent. Only the faint sound of leaves rustling in the wind could be heard. Every step he took echoed softly against the ground, making the silence feel even heavier.
After a few more steps, he finally saw Kagaya.
The man was lying on a low tatami mat in the shadow of the house, covered by a thin blanket.
His face was pale, almost as white as paper. His eye sockets were sunken, and his entire body was wrapped in bandages. The little skin that could still be seen had turned a faint purple.
He looked as if the illness had consumed him completely.
His breathing was weak and uneven, each breath slower than the last.
Raiden stopped a short distance away and stared quietly.
He had seen death many times before, but this sight was different. It left a strange heaviness in his chest.
After a moment, he stepped closer and spoke softly.
"Master."
It was the first time Raiden had said it with real respect.
His relationship with Kagaya had never been especially close, but he could not deny one thing.
Kagaya was a man who was willing to face death himself if it meant defeating Muzan.
And Raiden had already started thinking about whether there was any way to keep him alive.