Not long after Tanjiro returned to Sakonji Urokodaki's residence, his Nichirin Blade and official Demon Slayer Corps uniform were completed as well.
Through Sakonji and Hotaru Haganezuka, Tanjiro gradually came to understand just how revered his former senior—Ren Kuroda—was within the Demon Slayer Corps, and what the title of Pillar truly represented.
Once again marveling at Ren's overwhelming strength, exactly as he remembered it, Tanjiro strapped the box containing his sister Nezuko to his back and formally set out on his journey to hunt demons.
As for Ren Kuroda, aside from his daily sword training, his previously high attendance rate within the Corps dropped almost to zero. He spent nearly all his time at home.
He had already abandoned the idea of actively searching for the Twelve Demon Moons himself.
Rather than scouring the land, he preferred to wait patiently—hoping they would take the initiative, chase after Tanjiro, and walk straight into their own deaths.
To ensure he could reach Tanjiro's location as quickly as possible—before those demons were turned into the boy's experience points—Ren chose to remain home, quietly preparing for battle.
As for why he didn't simply follow Tanjiro directly, there were two reasons.
First, Ren worried that if he stayed at Tanjiro's side, the Twelve Demon Moons might sense danger and retreat.
Second, he was now a Pillar. Following a novice Demon Slayer around would inevitably spark rumors.
Ren didn't care about gossip itself—but the Demon Slayer Corps was still providing him with a steady stream of reputation points every day. The harvest wasn't over yet, and he had no intention of damaging his carefully maintained "perfect" image.
Under Ren's distant but watchful gaze, Tanjiro continued to grow at a steady pace—defeating the Swamp Demon, the Hand Demon, the Arrow Demon, and eventually the Drum Demon, who was later expelled from the ranks of the Twelve Demon Moons.
During this period, because of Tanjiro's movements, Ren even encountered the ultimate existence of this world—the Demon King, Kibutsuji Muzan—earlier than anyone else.
The man appeared as a pale, refined middle-aged gentleman, dressed in an impeccably tailored suit. To an uninformed observer, he might have seemed like nothing more than a cultured aristocrat.
Yet Ren immediately sensed an incomparably dangerous aura radiating from him.
As a swordsman, Ren could detect no flaws whatsoever.
In short, even if Ren activated his Half-Demon Transformation and used the Sesshō-seki, he was no match for Muzan.
Although the system bluntly informed him that defeating Muzan alone would be enough to complete his mission—after all, Muzan was far stronger than twelve subordinates—
Ren dismissed that advice without hesitation.
The gap in strength was obvious. Demons might be aggressive by nature, but Ren Kuroda was not an idiot who would willingly throw his life away.
However, while Ren possessed self-restraint, there were certainly others who didn't.
After catching the scent of his enemy, Tanjiro—still little more than a rookie—chased the big boss himself through several city blocks.
Just as Ren was lamenting the stubborn recklessness of the so-called Child of the World, worried the boy might die far too early—
Muzan Kibutsuji panicked the moment he laid eyes on Tanjiro's earrings.
That's right.
The final boss—the being feared by the entire Demon Slayer Corps—hesitated when faced with a rookie.
Even after Tanjiro provoked his killing intent, Muzan refused to pursue him personally, instead sending two subordinates in his place.
Was Muzan afraid it was a trap?A deliberate attempt to lure him out?
Ren didn't know what Muzan feared.
But one thing was certain—Muzan refused to act himself.
His two subordinates were swiftly killed.
After the Muzan incident, Tanjiro went on to meet Zenitsu Agatsuma and Inosuke Hashibira, both of whom had also passed the entrance trials.
Zenitsu Agatsuma was a timid-looking blond boy who practiced Thunder Breathing, one of the five fundamental breathing styles.
Inosuke Hashibira was his complete opposite—a battle-obsessed youth who wore a boar's head mask and wielded his self-created Beast Breathing.
Beyond their breathing styles, all three possessed unique innate abilities.
Tanjiro had an extraordinary sense of smell.Zenitsu possessed abnormally sharp hearing.Inosuke had a wild, animal-like sixth sense.
When the Drum Demon appeared, Ren—lurking in the shadows—initially planned to intercept it himself.
However, the system informed him that although the Drum Demon had once held the position of Lower Rank Six, it had already been expelled from the Twelve Demon Moons because it could no longer be "consumed."
Even if Ren killed it, the mission would not be completed.
As a result, Ren ultimately remained an observer—watching as Tanjiro and the others reversed the situation, defeated the demon, and traveled to a Demon Slayer Corps branch to rest.
Only then did Ren quietly withdraw.
Not long after Ren returned to the Demon Slayer Corps headquarters, a liaison officer hurried to his residence with urgent news.
The day before, traces of demonic activity had appeared on Natagumo Mountain.
Those who entered the mountain had begun vanishing without a trace.
At first, it was only ordinary villagers.
But when the Demon Slayer Corps dispatched members to investigate, even Demon Slayers began disappearing.
It was clear that powerful demons were active on Natagumo Mountain—creatures far beyond the level of ordinary Corps members.
After receiving this report, Ubuyashiki Kagaya decided that a Pillar must be sent to investigate.
Unfortunately, due to the recent surge in demonic incidents, the other Pillars were all tied up with urgent matters and unable to spare the manpower.
The only Pillar currently unoccupied was Ren—who had been staying home for some time.
As such, Ubuyashiki Kagaya hoped that Ren Kuroda would take on the mission.
Ren initially intended to refuse.
More than investigating Natagumo Mountain, he was far more concerned with finding the Twelve Demon Moons, as his mission deadline was rapidly approaching.
He firmly believed that as long as he continued tracking Tanjiro's path, the Twelve Demon Moons would inevitably reveal themselves.
The Drum Demon had already been removed from the list.
It wouldn't be strange if the remaining Moons appeared next.
After all, even Kibutsuji Muzan himself had crossed paths with Tanjiro.
Ren was utterly confident that Tanjiro would eventually face the remaining Twelve Demon Moons.
Then the liaison officer added quietly:
"But Lord Ren… the ones you asked me to keep watch over—Kamado Tanjiro and his companions—are also heading toward Natagumo Mountain right now."