In the unwritten rules of the Demon Slayer Corps, if a disciple fell and became a demon, then the master must bear full responsibility.
But this was not just a matter of responsibility.
For Jigoro, Kaigaku was once his pride, the successor he had placed high hopes in.
Even if that child had an extreme personality and was overly concerned with success and gain, he had always believed that under the tempering of Thunder Breathing, behind that distorted self-esteem, there was always a shred of protective goodwill.
"Old man...." Taka opened his mouth, wanting to comfort him, but found he had nothing to say.
The corpses of the demons had long turned to countless ashes, dissipating in the fog.
Yet, the silence in the courtyard was even more suffocating than the slaughter just moments ago.
"Taka...."
Jigoro looked up, his eyes filled with a dead, ashen stillness. "You should go back. I.... am a failure. There's nothing left I can teach you."
He looked down at his hands.
These hands had once slain countless demons, had gently wiped away the tears of young disciples, had sternly guided the hands that swung their swords.
"A successor of Thunder Breathing has become a Kizuki.... How terrifying is this..... I raised a monster.... I brought shame to Thunder Breathing, plunged the honor of all past Rumble Hashira into the mud...."
The old man slowly turned around and, limping, walked towards the interior of the dojo.
"I must go to fulfill.... my final duty."
Taka followed him all the way to the doorway.
He saw Jigoro enter his room and sit upright in the center of the tatami mat.
The old man loosened his upper garments, revealing that scar-covered, aged yet still strong chest.
He picked up a piece of white cloth and slowly began to wipe the Nichirin Sword that had accompanied him his entire life.
No words were needed… Taka already understood the old man's decision.
Seppuku.
This was the oldest, and most tragic and violent, way to atone.
It meant he would, in extreme pain, alone walk towards the end of his life.
"Won't you wait a little longer?" Taka stood by the porch, looking at the old man's silhouette. "The final battle is imminent. Perhaps you could end him with your own hands."
"No...." Jigoro's voice was calm, without a ripple. "That is Zenitsu's task.... As his master, the final response I can give that traitor is to use this old life of mine to wash away the filth he has left on this school."
He paused, then suddenly turned his head and showed Taka a smile with a hint of relief.
"Kid, thank you for showing me that Thunder Breathing.... will not be completely severed."
"The other sword forms are in the successive generations' Rumble Hashira books in my room. If you think they'll be useful, take them."
"Go. Don't look back."
Taka stood there, watching as the old man's hand grasped the tip of the blade.
He was silent for a long time. Finally, he bowed deeply towards the room.
"Thank you for your guidance, Kuwajima-sensei."
That night, the fog on Mount Momo ultimately did not dissipate.
In the dead of that deep autumn night, from within the dojo came only an extremely faint sound of a blade entering flesh, and the rustling sound of wind blowing fallen leaves.
…
A few days later, the Ubuyashiki Estate.
The atmosphere here was already stretched to the breaking point.
To welcome the coming final battle, all the Hashira and regular corps members were engaged in almost frantic special training.
The courtyard was filled with figures sweating profusely, and the clang of clashing blades.
Taka stepped into the estate in the lingering light of the setting sun.
He wore two swords at his waist, his expression calm to the point of being almost cold.
Anyone with a bit of strength could sense the change in him… if before he left he was an unsettled gale, now, around him faintly circulated a condensed and dangerous lightning pressure.
"Storm Hashira-sama! You've returned!"
Several corps' members in charge of training respectfully bowed.
Taka nodded slightly, preparing to cross the corridor to the master's residence to report on his mission.
However, a yellow figure suddenly rushed out from around a corner.
His movements were extremely fast, even carrying the sound of thunder.
"TAKA—!!!"
A miserable and piercing roar, filled with tears, exploded in the corridor.
Taka stopped in his tracks.
Standing before him was that always timid, scared, constantly weeping golden-haired boy… Agatsuma Zenitsu.
But Zenitsu now was not as he usually was.
He didn't, as usual, directly pounce and cling to Taka's thigh, begging him to put in a good word to make the training easier.
Zenitsu stared intently at Taka. Those eyes, usually filled with unease, were now bloodshot.
His whole body trembled violently. In his hand, he death-gripped a piece of wrinkled letter paper.
"You.... you really went to Mount Momo, didn't you?" Zenitsu's voice was hoarse beyond recognition, every word seemingly squeezed through his teeth.
Taka looked at him and did not answer.
"Speak! You bastard!" Zenitsu suddenly stepped forward and grabbed Taka by the collar. "Didn't you say you were going to learn Thunder Breathing! Tell me, were you really there?"
Taka remained silent.
His gaze fell on the letter paper in Zenitsu's hand. It was the final letter Jigoro had sent via his Kasugai Crow that very night.
"You.... did you watch him.... watch him do that?"
Zenitsu's voice was distinctly choked with tears. His whole body nearly collapsed to the ground, yet he still gritted his teeth and forced himself to hold on. "Tell me! They said Gramps, because of that traitor.... because of that damned bastard, committed seppuku! And.... and there wasn't even a second to cut off his head...."
"That was his choice." Taka finally spoke, his tone as always, calm, even somewhat cold.
To Zenitsu, these words were like a thunderbolt.
"You were there.... you were right there watching! Why didn't you stop him? Aren't you a Hashira? Aren't you strong?!"
Tears burst from his eyes.
"He may have had a bad temper.... may have always hit me.... but he was my only family! He was the best old man in the whole world!"
"How could you.... how could you just watch him die like that—!!!""
Anger and grief broke through his reason in an instant.
"You bastard—!!!"
Zenitsu suddenly swung his fist and heavily punched Taka's calm face.
Bam!
Taka didn't dodge, nor did he choose any means to absorb the force.
He took the punch head-on.
Because Zenitsu was in a state of extreme grief and anger, the force of this punch was immense. Taka's face was hit hard, his head snapped to one side, the corner of his mouth instantly split, and a trace of red blood seeped out.
"STORM HASHIRA-SAMA!!!"
The surrounding corps' members were startled by Zenitsu's action and quickly came to pull him away.
Zenitsu had completely lost his strength. He collapsed weakly on his knees before Taka, covered his face with both hands, and let out a wail like a wounded beast.
"Answer me.... why won't you speak...."
"Waaah.... Gramps.... Master...."
The crying drifted in the evening wind, echoing through the exquisite yet cold corridors of the Ubuyashiki Estate.
Taka looked down at the boy kneeling at his feet. He offered no comfort, no explanation.
He took the other Nichirin Sword from his waist and, along with a yellow-covered book from his chest, handed them to him. "Go and become stronger than anyone. Don't look back."
Taka walked around the sobbing Zenitsu and strode forward.
"Old man, this is all I could do."
"Whether he will truly transform or not is no longer something I can decide."
He murmured to the air, touching his slightly swollen lip.