Ever since a thousand years ago, when the failure known as Muzan Kibutsuji turned into a demon, the males of the Ubuyashiki family had been struck by a horrific curse. Every male infant born was weak and sickly, destined to die in infancy.
It was only after the clan followed the advice of a high priest and began marrying girls from a line of Shinto priests that the family avoided total extinction.
Even so, this only weakened the curse; it didn't break it. The boys no longer died as infants, but as they grew, the curse eroded their bodies, leading to frailty and eventual blindness. No male of the Ubuyashiki line had lived past the age of thirty in a millennium.
To truly break the curse, the source—Muzan Kibutsuji—had to die. This was why the family had formed the Demon Slayer Corps: to end Muzan and finally liberate their lineage.
"Your curse is very obvious and very powerful. With my current ability, I can't break it completely, but I can weaken it a bit," Goku replied seriously after a moment of careful observation.
A curse this potent was something even Grandpa Dumbledore might struggle to resolve. But Goku felt he could at least try to suppress its effects.
"You really are a miraculous child, just as Mita described. Would it be too much trouble to ask you to weaken this curse?" Kagaya Ubuyashiki coughed slightly, requesting with a gentle smile.
He didn't expect a full cure; he only hoped to recover enough health to gain the energy needed to trap Muzan and end the curse in his generation. The current nine Hashira were the strongest generation since the era of the first Breath users. They were his greatest hope.
"I won't let you help for nothing. Name whatever price you think is fair," Kagaya added. The Ubuyashiki clan had been a wealthy and powerful family for a thousand years; they did not lack gold. They funded the entire Corps out of pocket, as neither the public nor the government paid for the slaying of demons.
"I don't want money. I came here to train, to get stronger, and to fight powerful people," Goku thought for a moment. "If it's okay, I want to spar with the nine Hashira and learn their Breathing Styles."
He paused, then added, "But if they don't want to, that's okay too. You're a good person, so I'll still do my best to help you."
Goku still had a pile of Galleons in his box; he had no real need for more money.
"We are willing! As long as you can help Oyakata-sama, you can spar with us for as long as you like!" the nine Hashira promised immediately. To save their Master, they would give far more than just a sparring session—they would give their lives.
"That's great!"
Goku focused his mind, channeling the ki in his body as he began to chant:
"Finite Incantatem!"
A brilliant blue magical light enveloped Kagaya Ubuyashiki. The purple mark that covered over half his face began to recede, and his dull, sightless eyes gradually cleared and brightened.
Kagaya felt his body surging with vitality, as if he had reverted to his twenty-year-old self. Back then, the curse hadn't been as severe; he could walk unaided and see the world. Goku's magic had suppressed the curse enough to buy him perhaps an extra ten years of time.
"It's wonderful... I can see all of you again." Kagaya looked at the nine Hashira kneeling before him, his voice trembling with rare emotion.
The Hashira couldn't help but stand up in shock.
"Oyakata-sama!"
They saw their dying Master suddenly rejuvenated, his strength returned and his sight restored. This was all thanks to the miraculous boy standing beside him. Their eyes filled with profound gratitude as they looked at Goku.
"Thank you, Goku-san. Thank you for lifting this burden from me," Kagaya said, grasping Goku's hand and speaking with heartfelt sincerity. Perhaps he truly could end Muzan in his lifetime.
*Growl...*
Suddenly, Goku's stomach let out a thunderous roar. He had been up since dawn, fought a duel, and performed magic without eating breakfast. Even if he hadn't used much energy, he was starving.
"Mita, have someone prepare a feast," Kagaya laughed, turning to Mita. Mita nodded and hurried out of the courtyard.
"I imagine none of you have had breakfast yet. We shall eat together. But before that, let us address the matter of Tanjiro and Nezuko." Kagaya turned his gaze toward Tanjiro, who was still clutching his box.
"Oyakata-sama, my sister has never killed anyone! She's been helping me fight demons! Please, I beg you to let her continue!" Tanjiro dropped to his knees, pressing his forehead against the dirt.
Sanemi and the others remained silent. Normally, they wouldn't have let this slide, but Goku had just saved their Master. To demand the demon's death now would put them in direct conflict with their savior—a situation none of them wanted.
"Everyone, a letter has arrived from the former Water Hashira, Sakonji Urokodaki. I would like you to hear it," Kagaya said. His daughter stepped forward and began to read:
"I am Sakonji Urokodaki. Please allow Tanjiro to be with his sister. Nezuko maintains her human reason through sheer willpower. Even when starving, she has not eaten a human for two years. If she were ever to attack a human, Tanjiro Kamado, Sakonji Urokodaki, and Giyu Tomioka will commit seppuku as an apology."
"Tanjiro and Nezuko are members I have personally acknowledged. I hope you all can accept them as well," Kagaya said softly, looking for the Hashira's consensus.
Giyu, being one of the guarantors, naturally agreed. Shinobu, now knowing the truth, felt sympathy and nodded. Mitsuri followed the Master's lead, and Tokito was indifferent.
Gyomei, Sanemi, Rengoku, Iguro, and Uzui were still conflicted. In their eyes, if Nezuko killed someone, the lives of three slayers wouldn't bring the victim back. However, with both Goku and the Master protecting the siblings, their resolve to execute the demon was beginning to waver.