The development of events was broadly consistent with what Rei had anticipated.
The anime world was very large and also very small. While tens of thousands, even hundreds of thousands of Demon Slayer fans were spreading across every platform they could reach, actively telling anyone who would listen about episode nineteen, a significant wave of previously uninvested viewers was being pulled in by the noise.
Demon Slayer? It has become exceptional?
Were people not calling the plot formulaic and declaring Shirogane's creative output exhausted just a few months ago?
What exactly has changed?
The intensity of the conversation was greater than anything surrounding the Hunter x Hunter manga chapter in which Komugi and the Ant King died.
And it was not simply the existing manga and anime audience amplifying their own enthusiasm. The media across the Japanese anime industry had aligned in their assessment, and the overseas response was adding its own weight to the pile.
The anti-fan argument in Japan had spent months framing Demon Slayer as a derivative vampire story, which was a characterization that carried a particular irony given where vampires originated as a concept.
Foreign audiences, coming to the series without that framing, had found a natural point of entry. Several international broadcast markets had translated the word for demon in the series directly into their own local equivalent, and the response from overseas audiences to the latest episodes had been at least as intense as anything happening domestically.
A work becoming popular within Japan was one thing. Hikaru no Go had achieved that. Rei's works had in some cases been more popular internationally than at home, as Arcane had demonstrated. But reaching top-tier status both domestically and internationally at the same time, even briefly, was a different category of achievement entirely.
Demon Slayer had done it.
The prairie fire metaphor was not an exaggeration. For a full week the discussion volume did not drop.
Ion TV made the calculation quickly. The purpose of programming was viewership, and viewership existed to support advertising revenue. Demon Slayer had a ready-made audience that was actively growing. The documentary content and shopping programs filling the off-peak broadcast hours were pulled and replaced with reruns of the anime without ceremony.
This served a practical need. A large portion of the newly curious viewers in Japan had no way to access the series from the beginning. The tankōbon volumes and the anime home release were both only available up to the first volume. The rebroadcast schedule filled that gap.
Thursday arrived again.
Episode twenty of Demon Slayer began its broadcast.
This episode was not built on the same hot-blooded and emotionally overwhelming energy as the one that had preceded it. What it was built on was weight of a different kind.
At the close of episode nineteen, Tanjiro's Hinokami Kagura had appeared to cut Rui's head from his body. The episode had been constructed to feel like the protagonist's decisive victory, the emotional release the buildup had earned.
Episode twenty revealed the fuller truth of what had happened.
Rui had recognized in the final instant that he could not dodge the attack. He had used his own threads to sever his own head before the blade reached him.
A demon whose head was removed by their own action rather than by a Nichirin Sword did not die from it. Tanjiro, drained completely by everything the fight had cost him, was still in genuine danger.
Then Giyu appeared.
What followed was a demonstration of what a Hashira actually was. The Water Hashira moving at his full ability, without the restraint the series had shown in his earlier appearances, showed the audience a ceiling they had not previously been able to measure.
And then the episode turned, as the series always turned, toward the demon it had just destroyed.
Why had Rui, ranked Lower Five among the Twelve Kizuki, gathered a collection of weak demons and constructed this grotesque version of a household around himself?
The answer arrived through the memories of the demon he had called his sister as she reached the end of her existence.
Rui carried no memories of his human life. The transformation had taken those completely. But the loneliness remained. It had always remained. He had a sense, not quite a memory and not quite a feeling, that if he could experience true family bonds, the memories would return to him.
And so he had taken what he could find and forced it into the shape of what he was looking for, punishing every failure of performance with a demon's capacity for casual cruelty.
A game of playing house, conducted with the specific resources available to a demon.
This was what Demon Slayer consistently did. It spent the necessary time making the audience despise a particular demon, and then it used a much shorter stretch of time to make the audience understand them.
Most anime were content to establish how terrible a villain was. Very few asked why.
After episode twenty aired, the debut battles of Giyu and Shinobu Kocho concluded with the visual confidence of characters who had been restrained for a long time finally given room to move. Rui's inner world, glimpsed through the sister's final memories, settled into the audience alongside everything else the arc had delivered.
It was not as viscerally charged as episode nineteen. But it was not significantly less moving.
For an entire night following the broadcast, Demon Slayer occupied the top positions on every major trending list in Japan.
The Mount Natagumo arc had delivered the sibling bond between Tanjiro and Nezuko, the Hashira debut, and Rui's loneliness, and each of these elements had found its audience and continued circulating through them.
Rei's fans were focused on the plot.
The industry practitioners were focused on the results.
The previous week had established Demon Slayer as the most discussed anime property in the world. The question being asked in production companies and editorial departments across Japan was whether the episode twenty numbers would sustain what episode nineteen had started or represent a correction back toward the previous baseline.
The viewership rating for episode twenty came in at 7.05 percent.
On Friday morning, the practitioners who had spent months predicting the series' ceiling were largely silent, and the ones who were speaking were not doing so calmly.
"How is this possible? Two weeks. From 6.3 percent to 7.05 percent in two weeks."
"Is this the same industry I have been working in? Hunter x Hunter had an extraordinary reputation across its entire run and its ratings never moved like this."
"It is a different kind of work. When Hunter x Hunter was at its peak, I told my daughter to watch it with me. She could follow portions of it but the Yorknew City arc and the Phantom Troupe sequences lost her completely.
The battles of strategy and deduction in that arc require a level of sustained analytical engagement that children in primary school are not equipped for yet. Demon Slayer is genuinely different. She watches it, understands it, and cries at the demon memory sequences. Those are her favourite parts of every episode."
"Set aside the violence for a moment and the actual story structure of this anime is completely accessible. No barrier to entry, emotionally direct, and for a combat-focused series, the female viewer proportion is actually higher than the male proportion. That is the strangest part of all of this."
"You are saying the viewership surge is being driven by new viewers entering the series."
"A work with no barrier to entry has a naturally high follow-through rate once someone starts. That is how the audience compounds. But 7.05 percent is still a number I was not prepared to see."
"I cannot work this out. A derivative vampire story reaches seven percent viewership? Four consecutive anime from the same creator all reaching this level. How?"
"I cannot work it out either. But what can be done about it? The results are there and the Japanese audience has decided. And if either of us had been able to figure out what Rei was doing, we would not be sitting here. We would have been generating hundreds of millions a year from our own serializations long ago."
"I need to sit with this for a while."
The news of Demon Slayer breaking seven percent viewership moved through the industry rapidly and with considerable force.
Three months ago this series had been the target of sustained coordinated criticism. The argument had been that its plot was derivative, its premise was unoriginal, and its creator had exhausted his creative momentum. Now the results were on the board and the results were not interested in any of that.
In the Japanese anime industry, performance was the final language. Viewership ratings, sales volume, revenue generation. These were the standards that overrode everything else. The anti-fan commentary could continue.
The argument that Demon Slayer was a reskinned vampire story with a simplistic plot could be maintained indefinitely by anyone who wanted to maintain it. It was simply irrelevant now.
The viewers who had been watching the discourse from the outside and holding back their decision made up their minds after the seven percent figure was confirmed.
A series that reached this level of viewership deserved at minimum an honest look. If it turned out not to be for them, nothing was lost. But missing a work genuinely comparable to Hunter x Hunter because the comment sections had been loud in the wrong direction was a different kind of loss.
Saturday arrived.
The Dream Comic Journal sales figures for the previous week were confirmed. An increase of 1.8 million copies compared to the week before, closing at 23.98 million copies.
The weekly popularity vote for the Demon Slayer manga had reached 2.6 million votes.
The other competitors across the Japanese manga industry looked at these numbers and found themselves without a framework to place them in.
Something was wrong with this data. The rate of growth did not follow any pattern that normal promotional activity could produce. Even the most aggressive door-to-door campaign across the entire country should not have been generating acceleration at this rate.
But the facts were the facts.
In Rei's previous life, the annual tankōbon sales record of thirty million copies, set during the Marineford arc of One Piece, had seemed like a ceiling that would hold for a generation. Demon Slayer had not simply broken it. It had nearly tripled it, reaching eighty million copies in annual sales at its peak.
Rei had genuine affection for Demon Slayer as a work. But he was honest enough with himself to acknowledge that it was not, in his personal evaluation, the finest manga ever produced. There were works whose craft and reputation he placed above it without hesitation.
That personal assessment meant nothing in the context of what the numbers were saying.
Demon Slayer had demonstrated in his previous life that it was not a work every person would love. What it was, and what nothing else in the medium had ever quite replicated, was a work capable of being liked by the largest proportion of people simultaneously. The premise was accessible. The emotions were direct. The barrier to entry was essentially zero.
And the combination of those qualities, delivered with production quality at this level, could reach audiences that more complex and more critically admired works could never access.
Japan was replicating the same trajectory.
Among the six major manga companies, nobody could account for what was happening. Not the five competing publishers. Not Hoshimori Group itself. Not Misaki. Not Miyu.
But what every one of them understood from the vote count and the journal sales figures was the same thing.
The explosion of Demon Slayer's popularity appeared to be, in every measurable sense, only the beginning.
That night, Rei exhaled slowly.
The fatigue was physical. The temperature in June was part of it, but the larger part was the accumulated weight of news media interviews and manga tankōbon signing events across the past several days.
His hand had not fully recovered from the signing sessions before the next round of appearances had begun.
"Episode nineteen was a trigger. A promotional benchmark to get the fire moving. Every step from here is what actually matters," he thought, scrolling through the Demon Slayer anime discussion threads with quiet attention.
The previous life's success had not been automatic or inevitable. Demon Slayer had demonstrated genuine potential, but potential did not become global reach on its own.
In his previous life, the series had earned its anime adaptation through years of patient serialization and the slow accumulation of a dedicated readership. After the anime arrived and the reputation exploded, the resources had followed.
Shueisha's full institutional support. A production company operating at the highest level it had ever reached. A plot that continued improving as the cast expanded. The combination of capital, craft, and timing had been necessary in full.
Remove any one element and the outcome would have been different.
In this version, the capital side was more favourable than it had been. Hoshimori Group had now seen enough to understand what Demon Slayer could become. Whether the copyright structure allowed them to participate meaningfully in the globalization wave or not, declining to support it was not a rational option for their shareholders. A result declining from here would be far more damaging to them than the discomfort of working hard on someone else's behalf.
The global promotional campaign for the manga Rei did not need to manage directly. Hoshimori Group would handle the path forward on that front with the full motivation their financial interests provided.
The anime was a separate matter. Rei had already committed funds and was in the process of establishing a dedicated overseas operating company for Demon Slayer: Kimetsu no Yaiba.
When that structure was in place, the international rollout would begin properly and officially rather than through the organic spread that was already happening.
The Japanese anime market in June was operating at a different energy level than it had been in May. The Demon Slayer explosion had functioned like a stimulant injected directly into the industry's bloodstream.
Under the combined promotional efforts of Rei and Hoshimori Group, new viewers were entering the series in significant numbers every week.
Thursday came around again.
By evening, the Demon Slayer fan communities were already moving.
"Will the Mount Natagumo arc conclude this week?"
"Rui's memory sequence ran quite long."
"I am not particularly focused on Tanjiro's side of the plot right now. I want more of the Hashira and more of Nezuko."
"Nezuko is the little angel of this entire series."
"Shinobu Kocho has become the most popular female character in the Japanese anime industry this month. That happened remarkably fast considering we still know almost nothing about her."
"Her identity is a secondary concern. What matters is the composure, the charm, and the specific quality of her personality where she says something cutting while wearing a pleasant expression. The character image is immediately distinct."
"I will simply say it plainly. I enjoy Shinobu Kocho's character. She speaks as though she is quietly mocking whoever she is talking to and her expression suggests permanent mild contempt. Apparently this is exactly what I want from an anime character."
"Read the room."
"Looking back at the Mount Natagumo arc as a whole now, the quality gap compared to the earlier episodes is clearly visible. Is Shirogane-sensei developing during the serialization itself?"
"The Mount Natagumo arc has a completely different quality to it. Something shifted."
"Anyway, episode twenty-one airs this week. What happens to the viewership rating? Does it continue rising?"
"That seems unlikely. It is already at 7.05 percent. The twentieth episode benefited from the momentum episode nineteen created. By the twenty-first episode, with the arc reaching its conclusion, the elevated energy should have settled and the numbers should reflect that."
"I would be careful about that prediction. My eldest daughter and my youngest son are currently sitting in front of the television waiting for the episode to start. A work that can do that to both of them simultaneously is not something I am willing to dismiss."
"Wait for tomorrow's noon report. If the viewership rating increases again, the shape of this industry is going to look different than it did a month ago."
That night, a large portion of Japan's anime audience, covering genuine fans, curious newcomers, and the critics who had maintained their skepticism throughout, positioned themselves in front of their televisions before the broadcast window.
As eight o'clock approached, the volume of discussion on the forums dropped steadily. The conversation moved from the screen to the living room.
Across the country, viewers settled in and waited through the Demon Slayer merchandise segment that Ion TV was running in the lead-up to the broadcast, watching the clock.
Eight o'clock arrived.
The screen held for a moment. The opening theme began.
For the competitors and critics who remained hostile to Rei's position in the industry, the focus was not on the episode itself but on the result it would produce.
The viewership data from the past two weeks had been genuinely alarming to anyone invested in the idea that Demon Slayer had a ceiling. But this was the third week following episode nineteen. The surge in attention that a single exceptional episode could generate had a natural duration.
The plot had reached the closing stages of its arc. The conditions that had produced 7.05 percent were not going to maintain themselves indefinitely.
Demon Slayer had produced strong work and strong numbers. But strong work and a temporary spike in attention were different things from a series that had fundamentally changed its position in the market.
This was the position many of them were holding. Acknowledging the results while privately expecting the correction to arrive soon. A flash of exceptional performance that would eventually settle back toward the series' established baseline.
It was, in some ways, the same mentality that had surrounded Demon Slayer at the peak of its popularity in Rei's previous life. Conceding the numbers. Dismissing the longevity. Waiting for it to return to what it had been before.