Ever since he had begun working on his claws, he no longer sought out sparring matches.
In the past, Takeo had sought out sparring matches with others to improve himself. But now, he had a new master—and a new training partner.
After putting him through agonizing training, the Wolf seemed to have accepted him as a disciple. Every time Takeo entered the consciousness space, the Wolf would teach him something new.
And then… the Wolf would beat him mercilessly with a wooden sword.
It wasn't as though Takeo had never been struck during training with Kyojuro, but whether it was a trick of the mind or not, he always felt that the Wolf's blows were far harsher.
Takeo sometimes wondered if this was the Wolf's way of taking revenge on him for choosing the "no death" ending.
Of course, that was only a joke.
In any case, Takeo had no interest in sparring with his fellow Hashira for now. Naturally, he turned down Sanemi's demand.
But Sanemi thought otherwise. Veins bulged across his forehead as he barked,
"Huh?! Are you looking down on me, you little bastard?"
"…That wasn't my intention. Instead, Sir Wind Hashira, perhaps you should reflect on yourself and ask why you would think that way."
"Very good. You've angered me, brat. Now fight me—immediately!"
Sanemi's lips twisted into a savage grin, his fingers flexing like a street brawler itching for a fight.
Takeo sighed and opened his mouth to reply, but at that critical moment, Kocho Shinobu stepped gracefully between them, her voice calm but firm.
"I'm sorry, Mr. Shinazugawa, but perhaps you should save your 'sparring' with Kamado-kun for another time. I have something I need to discuss with Kamado-kun first."
Shinobu Kocho stepped lightly between Sanemi Shinazugawa and Takeo, her expression apologetic. Seeing her look, Sanemi Shinazugawa clicked his tongue in dissatisfaction. Without another word, he turned on his heel and stalked off.
Once Sanemi Shinazugawa was gone, Shinobu turned back to Takeo with a gentle smile.
"I hope I didn't trouble you?"
"No—thank you, Miss Shinobu. Otherwise, things would have gotten very troublesome for me."
Takeo bowed his head slightly in gratitude.
He truly had no easy way of dealing with Sanemi Shinazugawa. To be honest, his strength was only slightly above the Wind Hashira's. If they actually fought, winning would only mean being hounded for rematches. But if he feigned defeat, Sanemi Shinazugawa would almost certainly see through the act, which would cause even greater problems.
Better to avoid the fight entirely. Shinobu's timely intervention had spared him considerable trouble.
"Miss Shinobu, was there something you wanted from me?" Takeo asked after thanking her.
Shinobu's smile softened into something more serious. "Yes, there is. Please come to the Butterfly Mansion and sit with me for a while. Regarding your blood… we need to have a proper talk."
…
During the year that Takeo had been searching for a way to reinforce his claws with metal, Shinobu Kocho had not been idle either.
Using Takeo's blood, she had experimented—mixing it with certain rare medicinal ingredients—to create several vials of a unique healing formula.
The effect of this special medicine was…
"It allows a person to recover from even the most severe injuries in a short period of time. Although my experiments with mice and rabbits confirmed that it has the side effect of shortening lifespan, at the very least… it can save someone who would otherwise be doomed to die."
Shinobu Kocho placed a vial of the special medicine before Takeo as she spoke.
The medicine she had developed took the form of a syringe.
Two syringes, each about the thickness of a finger, were neatly laid out in front of him. Picking one up delicately, Shinobu explained:
"The method of use is direct injection. Once injected, the drug will take effect within five to ten minutes, depending on the patient's physical condition. When it activates, injuries will begin to heal rapidly. Within half an hour at most, the body will recover to its full state."
She held the syringe out to Takeo.
He inspected it carefully before looking up. "Wow.. and the only side effect is a shortened lifespan? There's nothing else? No other complications?"
"No," Shinobu replied at once. "I have conducted many experiments and comparisons. I am certain that is the only side effect."
"Then what exactly are you asking of me, Miss Shinobu? Do you want me to stay here and produce more of these healing serums?" Takeo asked.
Shinobu shook her head. "No. On the contrary, I want Kamado-kun to keep this matter a secret."
Takeo raised his eyes to her. "Why?"
"Because your situation cannot be revealed to anyone—not even those closest to you. The secret of your blood must remain hidden as well."
Shinobu Kocho spoke with rare gravity, the usual smile vanishing from her face.
As a physician, she understood better than anyone what Takeo's existence represented to the entire field of medicine.
Demons existed, yes—but their blood could not be transfused into humans. Aside from Muzan Kibutsuji himself, demon blood carried no beneficial effect for humans. And even then, any such "effect" only ever transformed people into demons.
Takeo, however, was different.
When diluted and properly refined, his blood could be crafted into a miraculous potion—one that granted temporary, extraordinary regenerative power.
It didn't turn the user into a demon. It carried no side effects beyond an unseen, intangible reduction of lifespan. In every other respect, it was nearly perfect.
Humans had no defense against the allure of such a medicine.
If word of this ever spread, the danger Takeo faced would not come from demons alone.
"…What about you?" Takeo asked quietly.
At that, Shinobu's smile returned. "I will keep this secret myself. You need not worry, Kamado-kun. As for the potion, however, I hope you'll leave enough blood for me to create more.
"At the very least, there should be three vials prepared for each Hashira."
"The Hashira? Only the Hashira? What about the ordinary Corps members?"
"…Kamado-kun, if even the ordinary members were supplied with this medicine, then your life would be reduced to nothing more than providing blood."
Shinobu Kocho spoke the truth plainly.
A large amount of blood was required to create each dose of the special healing serum. The only reason she had been able to produce as many as she had was because Takeo had arranged for the Kakushi to deliver his blood to her at regular intervals.
And even so, all of that had yielded fewer than ten doses.
If the entire Demon Slayer Corps were to be supplied with this miraculous medicine, it would require Takeo to give blood every single day, endlessly.
Even if Takeo himself wished to make such a sacrifice, Shinobu would never permit it.
Takeo was human—at most, a human with unique abilities. He should not be treated as a resource to be drained.
"…I understand."
Seeing Shinobu's determination, Takeo said nothing more.
He simply rolled up his sleeve, exposing the veins in his arm, and asked, "How much blood do you need?"
"Even with your regenerative ability, Kamado-kun, you'll need to remain here for three days. During that time…" Shinobu's eyes softened, her voice gentle but firm. "…I will have to work you quite hard."
Then, in a gesture of deep respect, she bowed to Takeo.
For no matter who it was—anyone willing to sacrifice themselves for the sake of others deserved her respect, and the respect of all.