"Kamiya-san was truly incredible," he said after finishing reading all the memories, up to the moment his brain ceased to function.
A clear sign that the demon slayer was definitively dead.
'He knew he was going to die, and yet… he gave everything he had against me, without even thinking of fleeing…'
A foolish but courageous act.
Doma felt respect for Kamiya, but also regretted his stubborn refusal to become a demon.
A waste of potential.
Of course, he could have forced Kamiya to become a demon after defeating him.
But…
'He would no longer be Kamiya Rengoku…'
Logically, Doma had nothing to lose in this matter, but Jay's memory pushed him to make a decision based on "emotions" rather than "rationality."
That's why Doma respected Kamiya's wish to remain human and did not transform him after brainwashing.
"*Sigh* Indeed… it's too bad he had to die here."
Even while complaining, Doma could do nothing more about it. After all, Kamiya was now dead.
Just thinking about it, a strange glint flickered in Doma's eyes as he glanced at the decapitated body.
Unfortunately, that emotion quickly faded, and the dark abyss of his heart reclaimed its rightful place.
Beyond his child and breathing techniques, Doma had also discovered several things in Kamiya's memories.
"Hmm… a special sense of smell."
Kamiya had been able to track Doma's movement speed thanks to his abnormal sense of smell. This was also why he hadn't immediately called Doma a liar. He could sense the demon's sincerity from the start.
'A troublesome ability… but he won't be the only one I'll face.'
Doma was referring to abilities like Zenitsu's ears, a problem he decided to leave for his future self to handle.
"Unfortunately, Kamiya didn't know the location of the Demon Slayer Corps' headquarters."
A logical situation, since he wasn't a true Hashira according to their organization's rules. Besides, Muzan had spent centuries searching for that place.
It would be strange if Doma managed to locate it on his first encounter with the Demon Slayer Corps.
However, he had learned the locations of a few small Demon Slayer Corps outposts. There were also several temporary rest points for the organization's members that Kamiya had visited since the start of his career.
Doma recalled that Muzan wanted those places destroyed in retaliation for the death of Upper Moon Six.
Doma thought for a moment, then showed a troubled expression.
"That's interesting, but I'm too lazy for that… and it's pointless."
Those small outposts, even if destroyed, would be rebuilt in greater numbers a few years later. Pursuing them out of mere spite made no sense.
The only truly useful thing would be to kill a lot of people and seize their breathing techniques, as that would deter demon slayers and strengthen him.
But Doma wasn't interested in such a massive task, which would force him to leave his cult for a long time.
He decided to raid a few outposts when he had some spare time and send orphans there to be trained.
'That's indeed ideal, since I won't have to spend anything, and the Demon Slayer Corps will take care of everything.'
All he had to do was ensure the fanaticism of the children he sent, and Doma found this idea increasingly appealing, especially as he remembered he would soon have a child of his own.
"However, I'll act like I don't know anything in front of Muzan, haha," Doma chuckled, setting the matter aside.
He felt slightly guilty toward Muzan. Even though Muzan wasn't aware of the events of that night, he would be frustrated to learn of Doma's inaction against the overly bold Demon Slayers recently.
'Mhm mhm~ I'll just work harder in the future through the cult and provide more money for his experiments.'
Doma nodded to himself, having convinced himself of the nobility of his insubordination.
He left the rooftop destroyed by his fight with Kamiya with a light step and returned to the bustling street.
As for Kamiya's body? He had destroyed it with ice. He even took the time to eliminate a suspicious crow in the night sky.
Doma didn't want any information about him falling into the hands of the Demon Slayers.
He knew very well how valuable information was in a fight. Even Muzan had lost because of that factor.
…
Days passed quickly after the festival.
Doma was alone in the cult's reception hall after a day spent overseeing his followers.
A routine already ingrained in him.
Currently, he was facing a beam of sunlight streaming in from outside.
"Again… one more time…"
After the battle against Kamiya, he had decided to take his training more seriously, especially to perfect his defensive power, the vector.
Some might call him cowardly, but Doma would say he was cautious… excessively so.
"Ugh… damn, it burns…"
After about forty seconds, the flesh on his hand had been burned by the beam of light filtering through the monastery's walls.
Doma looked at his hand with frustration, gritted his teeth, and started again as soon as his regeneration allowed him to continue.
The cycle repeated until evening.
This masochistic act didn't come out of nowhere. The vector power drew its essence from manipulating the direction of all things.
Doma knew, thanks to his 21st-century knowledge, that everything that moves follows a direction. That included sunlight and its components.
'The… the universe is in perpetual motion…'
Even a seemingly inert body moves at the cellular, even atomic, level.
This truth alone showed the terrifying potential of the vector power, wasted by the ignorance of the Hundred-Eyed Demon.
"Still… it's hard for me to redirect the sun's 'properties' for long, and this is just my hand…"
His goal in this masochistic training was to apply the vector power to his entire body for a full day.
At first, Doma even hoped to use it like Gojo Satoru's Infinity or Accelerator from Toaru no index.
But the task was colossal.
He had to filter out the dangerous particles emitted by sunlight and maintain that focus 24/7.
Doma sighed before taking notes in a small notebook.
He recorded that he had lasted forty seconds.
"Phew… I can conquer the sun."
No sooner had he uttered those words than a "gaze" fell upon him, and he was abruptly teleported by Nakime.
Muzan had summoned him.
Yet Doma didn't panic.
It was impossible for Muzan to know about his training against the sun, which he considered an absolute secret, to be censored in his mind like any act of betrayal.
"Doma…" said a masculine voice, though it came from a woman dressed in traditional attire.
Muzan, in his female form.
"Good evening, Muzan-sama~ What brings me to your summons?" Doma replied with a slight bow after landing in Nakime's domain.
He was already perfectly familiar with the place, having delivered several scientific devices over the past month.
"I summoned you because of an issue concerning your cult… and something else."
Muzan pulled a pamphlet from his chest. Doma couldn't help but sneak a glance, purely out of scientific and cultural curiosity.
Fortunately for him, Muzan wasn't interested in such things and turned a blind eye to this small act of voyeurism.
"Oh… you received one of the pamphlets our followers distribute to outsiders. Are you interested, Muzan-sama~?"
After locking eyes with Doma's multicolored gaze, Muzan slightly furrowed his delicate brows.
The emotionless demon's jest didn't offend him, but he chose to set boundaries with a subtle warning through his gaze.
The effect was immediate. Doma lowered his eyes, like a student caught by his teacher in the middle of class.
After calming Doma's antics, Muzan chose to refocus the discussion on the main topic.
"I believe I was clear about discretion…"
Doma scratched his head with a feigned air of embarrassment, a gesture Muzan knew perfectly well thanks to his partial access to the emotionless demon's mind.
"I've spent all these months in my monastery, Muzan-sama, but it's possible that…"
Doma explained the situation with his cult. Muzan listened calmly. After a brief silence and a stare-down, the demon progenitor spoke:
"I want you to step down from your duties as cult leader within a decade and take the vacant position of Upper Moon Six."
This announcement didn't surprise Doma. He had anticipated it and made arrangements.
The cult would soon elect a temporary leader until his son came of age.
For now, Kikyo seemed the most practical candidate for the role.
"No problem, Muzan-sama," he replied calmly.
"I don't want any—"
"Wait, you're serious?" Muzan's voice and perplexed expression had something cute… and oddly pleasing to watch.
Doma gave a faint smile inwardly.
Even if one day he had to eliminate Muzan, he couldn't hate him: after all, the demon had been a true benefactor, both for him and his cult.
"Since there's no issue, you may leave," Muzan said, turning his back, a slight blush coloring his cheeks.
It didn't take a genius to guess that Muzan had read Doma's thoughts about him being "cute."
The Demon King was annoyed and embarrassed by the situation.
Unfortunately, Dōma didn't notice, as he would have laughed at this side of Muzan.
However, the emotionless demon then addressed him to bring up another topic:
"Wait a moment, Muzan-sama."
Muzan barely turned, casting a curious glance over his shoulder.
"I'd like to meet Kokushibo-sama, but… he wasn't willing to."
After his fight against Kamiya Rengoku, Doma had decided to refine two elements of his style: the vector power and Tessenjutsu, his close-combat art.
Unfortunately, neither Akaza nor Kokushibo wanted to see him.
"You wanted to see him? Like a Lower Moon, haha."
Muzan's laugh was terrifying but held a peculiar charm in his female form. After a moment, he calmed down:
"You don't seem to have thoroughly checked the memories I implanted in you… Lower and Upper Moons have special privileges in the Infinity Castle."
Muzan said no more and left the scene, visibly in a good mood.
Doma stayed behind, reviewing the information implanted in his mind.
A genuine smile spread across his face: now, he could become Kokushibo's guest.
He had become qualified.