Zenitsu Agatsuma was a boy Tanjiro had met during the chaos of the Final Selection, a boy whose life he had even saved. Despite Zenitsu's nervous exterior, Tanjiro had seen a flash of his incredible speed and knew there was more to him than met the eye.
"We... we all passed the assessment," Zenitsu's words surprised Tanjiro. His main goal in coming to Mount Fujikasane was to join the Demon Slayer Corps. The sudden, horrific attack had made him fear the worst, but somehow, he had succeeded. He had fulfilled his promise to his master. A wave of relief washed over him. The next step was simple: he would return to Mount Sagiri, reunite with his sister, Nezuko, and together, they would begin their journey.
"You're awake."
Before Tanjiro could get lost in his thoughts, a cool female voice spoke. A woman wearing a butterfly-patterned haori stood in the doorway. A calm and elegant aura emanated from her, and the air in the room seemed to grow colder in her presence. She was clearly not just a member of the Demon Slayer Corps, but one of its top experts.
"Hello, Tanjiro," she said with a serene smile. "My name is Shinobu Kocho. I am the Insect Hashira, one of the Nine Pillars of the Demon Slayer Corps, and I am also the leader of the medical team."
The title made both Tanjiro and Zenitsu gasp. Tanjiro knew from his master that the Hashira were the strongest fighters in the entire organization. His primary reason for joining was to find a cure for his sister, but he knew to show respect.
"Insect Hashira-sama, hello," he said, his voice calm despite his surprise. "You came to see me because..."
"I have many reasons for coming to see you," Shinobu interrupted gently, though her smile didn't quite reach her eyes. "But first, there are some things you need to know." Her elegant face grew a little colder. "Last night, at the same time you were participating in the selection on Mount Fujikasane, there was an attack."
She paused, letting him absorb her words. "The target was Mount Sagiri. The home of your master, Sakonji Urokodaki."
The words hit Tanjiro like a physical blow. He had felt that something was terribly wrong during the attack, but he never imagined this.
"Senior Urokodaki sent a message to the Corps immediately, and we dispatched three of our Hashira to provide support," Shinobu continued, her voice steady and clinical. "But the demon sent to attack was incredibly powerful. It was one of the Twelve Kizuki, a member of the Demon King Muzan Kibutsuji's personal guard."
Her gaze fell on Tanjiro, whose eyes were now wide with dawning horror. "Senior Urokodaki... and your sister, Nezuko Kamado... are now missing. Not only them, but the three Hashira we sent to help have also vanished."
The world seemed to fall away. Tanjiro and Zenitsu were both left in a state of stunned, horrified silence. They had just joined the Demon Slayer Corps, an organization dedicated to fighting demons. To hear that even its strongest members, the Hashira, had been defeated and captured was a terrifying revelation. For a moment, countless thoughts flooded Tanjiro's mind—his master, his sister, the Demon King Muzan Kibutsuji—before his mind went completely blank.
"Tanjiro! Tanjiro!" Zenitsu cried, frantically shaking his friend's arm.
After a long moment, Tanjiro finally came back to his senses, but the boy who had woken up just minutes before was gone. The kindness and gentle warmth in his eyes had been completely extinguished. All that remained was a cold, endless hatred for demons.
If not for demons, he would still be living a peaceful life with his family.
If not for demons, he and his sister would not have had to suffer.
If not for demons, his master and Nezuko would not be in the hands of a monster, their fates unknown.
"Tanjiro, I have something to ask you," Shinobu's cool voice said, cutting through his silent rage.
Meanwhile, in the Infinity Castle, the bizarre and incomparable music of a biwa resounded as space warped and overlapped. The Twelve Kizuki, who had been dispatched on their missions, reappeared, their eyes exceptionally sharp.
For years, under the leadership of the old Muzan, they had been forced to hide like rats in a sewer. They possessed nearly immortal bodies and incredible power, yet they were always the ones being hunted. But after the previous night's battle, a coordinated strike that had crippled their enemies, everything had changed. For the first time, they felt a true sense of pride in being demons.
A low, piercing roar echoed through the impossible space as a high platform rose from the ground. Upon it, a throne interwoven with blood and bone crashed into existence. A tall figure was half-reclining on it, his expression languid, his eyes shimmering like distant stars.
"Master!"
In perfect unison, the Twelve Kizuki dropped to one knee. This time, even the proud Upper Rank One, Kokushibo, knelt without hesitation. After witnessing his master's brilliant strategy and overwhelming power firsthand, the man who was devoted only to strength truly understood what it meant to be strong. It was not merely combat ability, but strength of mind, strength of will. To plan in the shadows and achieve a flawless victory miles away. At that moment, Kokushibo's loyalty to this new Muzan was absolute.
"You may all rise," the calm voice from the throne said, as if the absolute reverence of the most powerful demons in the world was nothing more than a passing glance in a mirror.