Giyu stood in the bamboo grove behind Kyogoku House, the night wind brushing the hem of his black kimono, carrying a faint chill.
Between his fingers, he held the small piece of candy Shinobu had secretly slipped him during their walk the previous night. Under the moonlight, its golden wrapper shimmered softly—though he couldn't taste sweetness anymore, just holding it gave him a trace of daytime warmth.
Suddenly, a sharp sting spread across the back of his neck, like an icy gaze sweeping over him.
He snapped his head up toward the sky. The night was deep, dotted only with a few faint stars—nothing seemed out of place.
"Was it my imagination?"
His dark-blue slit pupils narrowed, a glint of alertness flickering in them. Ever since becoming a demon, his senses had grown keener than any human's. That gaze, though faint, carried a familiar, oppressive aura—the unmistakable pressure of Muzan.
He quickly steadied his breathing, slipped the candy into the inner pocket of his kimono, and turned back toward his room.
He couldn't allow even a flicker of emotion to show. Muzan's consciousness could surface at any moment, and the slightest sign of oddity might raise suspicion.
Just as he sat down, hurried footsteps echoed outside the door—then a loud bang as it was shoved open.
Akaza stood in the doorway, short pink hair tousled, a trace of battle aura still clinging to him. He looked like he'd just returned from a fight, his voice dripping with irritation. "Mushiki, why didn't you finish off that Stone Hashira in North Village Street?"
Giyu looked up, his tone calm as ever. "Muzan-sama ordered us to retreat. I followed his command."
"Followed orders?"
Akaza sneered, stepping closer as his fists tightened. "You let him go on purpose, didn't you? That Stone Hashira was already exhausted—one more strike and he'd be dead! What's your excuse?"
Giyu didn't rise from his seat. "Akaza, your task is to hunt the Hashira. Mine is to oversee the Entertainment District. The matter in North Village Street is over—there's no need to dwell on it."
He carefully avoided Akaza's eyes, keeping his voice steady and emotionless. He knew Akaza's temper—impulsive, but utterly loyal to Muzan. If he sensed anything strange, he would report it immediately.
Akaza stared at him for several seconds, trying to find some flaw in his expression. But Giyu's face remained cold and blank, betraying nothing.
"Hmph. It better be that way," Akaza finally grunted, turning toward the door. "Muzan-sama is investigating the Demon Slayer Corps' hideouts. If you notice anything unusual, report it immediately. Don't mess this up."
"Understood."
Only after Akaza's footsteps faded down the corridor did Giyu slowly exhale.
That confrontation hadn't been random. Akaza's questioning likely came from Muzan himself. Muzan must have already been probing for details about North Village Street. This was a warning—his first real sign of danger. He would need to be even more careful from now on.
The next night, Shinobu arrived at the entrance of Kyogoku House right on time, holding the third vial of pale-green Cellular Illusion Serum.
"Sorry, I'm a little late," she said with a light laugh. "There was a strange peddler on the road. He kept staring at me, so I took a detour."
She smiled as she spoke, deftly rolling up Giyu's sleeve and inserting the needle into his vein. "But it's fine. I went around the long way—no one followed me."
Giyu's pupils narrowed slightly. "What kind of peddler?"
"Gray clothes, a scar across his face. He didn't look very friendly," Shinobu replied, recalling the encounter while pushing the serum slowly into his arm. "He asked if I was here to see 'Mushiki-san.' I pretended not to know the name and left."
A cold weight settled in Giyu's chest. He recognized that peddler—an informant in the district. He'd deliberately left the man alive to learn who he worked for.
Was it Muzan? The government? Or perhaps… Oyakata-sama's network?
Even with her caution, Shinobu had been noticed.
He reached out and gently brushed her hair, his voice calm but carrying a trace of urgency. "Don't come here again unless it's absolutely necessary. It's too dangerous."
"Alright, I understand."
Shinobu nodded, not arguing. From her pouch, she pulled out a small folded slip of paper and slipped it into his hand.
"This is Lady Tamayo's latest research update," she whispered. "She believes the Cellular Illusion Serum can be improved—extended to last twenty-four hours. But she needs more samples of Muzan's cells to do it. Can you… get them?"
Giyu tightened his grip around the paper. The handwriting was Shinobu's—elegant yet steady.
He knew what she was asking. To obtain Muzan's cells, he would have to get close to Muzan himself. It was an enormous risk.
But it was also their only chance to make the serum stronger—to give him a real shot at breaking free from Muzan's control.
After a brief silence, he lifted his arm.
"Would mine work?" he asked quietly.
"I'm Upper Moon Two. There's plenty of Muzan's cells in my body—they should work as samples."
Shinobu lowered her gaze, thinking for a moment. "Technically, that should be fine."
Giyu nodded slightly. "I'll give you the blood sample when you leave. You should head back first."
"Alright."
Watching Shinobu's figure disappear into the night, Giyu didn't return to his room right away. Instead, he walked toward the side gate of the courtyard—he needed to confirm whether that informant was still following her.
Sure enough, in the narrow alley not far from the gate, the scar-faced peddler was peering around the corner, keeping his eyes fixed in the direction Shinobu had gone.
Giyu's eyes turned cold. With a flick of his fingers, he formed a thin blade of water and silently sent it flying toward the man's ankle.
"Ah!"
The peddler cried out and collapsed, clutching his bleeding leg. By the time he scrambled up again, Shinobu had vanished at the end of the street, and Giyu had already returned to Kyogoku House.
The peddler rubbed his ankle, confusion clouding his face. Still, he didn't dare linger—he limped away quickly, his mind racing. Whoever attacked him had done it without sound or warning. That could only mean one thing: this place was dangerous.
He had to report to his master immediately—report that "Mushiki-san met with an unknown woman."
In the following days, Giyu could clearly feel Muzan's probing growing more frequent.
First, he was ordered to go to the Eastern Territory to "eliminate the remaining forces of the Demon Slayer Corps." But when he arrived, he found nothing there except an abandoned hut.
Then, Muzan had him audit six months of Kyogoku House's accounts, demanding every single expense be checked line by line.
That wasn't the kind of work an Upper Moon should ever be assigned—it was a test. Muzan was watching his reactions.
Giyu complied with everything. When he went to inspect the hut, he deliberately "let several imaginary slayers escape." When reviewing the ledgers, he marked a few "suspicious" entries on purpose, playing his role as a dutiful subordinate.
But he knew this was only temporary. Once Muzan's doubt took root, it would never fade easily.
That night, as planned, Giyu left a hidden signal in the bamboo grove behind Kyogoku House—a scale-shaped mark that only the Serpent Hashira, Iguro Obanai, would recognize.
The message read: "Muzan suspects me. Possible movements soon. Obtained information about his Upper Moon reallocation—forces shifting between East and West. Urgent: relay to Oyakata-sama."
He needed to deliver the critical intelligence before anything happened to him.
Just as he finished, he heard footsteps behind him—steady and deliberate.
Turning around, Giyu saw Kokushibo standing at the entrance to the grove, long blade in hand. Six calm eyes fixed on him.
"Your aura has changed recently," Kokushibo said, his tone emotionless.
Giyu's heart tightened, though his face stayed impassive. "Changed? In what way?"
"Before, your aura was cold—like ice."
Kokushibo stepped deeper into the grove, his eyes briefly flicking toward the scale mark on the ground. He didn't ask about it, but Giyu could tell he'd noticed.
"Now there's a trace of warmth in it," Kokushibo continued. "Like human emotion."
Giyu paused before replying evenly, "Maybe it's because I've been handling matters in the district lately. I've had to interact with more humans."
Kokushibo didn't question further. He nodded once. "Muzan-sama has taken a special interest in you lately. Make sure you don't make any mistakes."
He turned to leave, then added without looking back, "Your Moon Breathing has improved. Next time we spar, we'll attempt the complete form—Moon Breathing: Thirteenth Form."
"Understood."
Giyu watched him go, the weight in his chest growing heavier. Kokushibo's perception far exceeded his expectations—he could sense even the faintest shifts in aura.
If Muzan asked, would Kokushibo mention this change? That would be another danger waiting to unfold.
Late at night, Giyu touched his chest. Inside his kimono were three things: the piece of candy from Shinobu, Tamayo's research note, and the coded message for Obanai.
Those were all he had left—his only comfort, his reason to keep fighting.
Then it struck again—sharp, cold, and unmistakable.
That piercing sensation at the base of his neck. Stronger than before.
This time, he didn't mistake it for paranoia. Muzan's consciousness was invading his mind, probing through his memories. Muzan was near.
Giyu concentrated all his will, pushing the harmless fragments of memory—those Muzan might expect to find—toward the surface, hiding everything else deep within.
He could feel it—the alien presence slipping through his thoughts, rummaging through his memories like icy claws. Every touch sent waves of pain through his entire body.
Minutes—or perhaps hours—passed before the presence slowly faded away.
When he opened his eyes, his forehead was slick with sweat. His back was soaked.
There were things Muzan could never know—like the locations of Corps headquarters, the residences of the Hashira, or the names of those tied to his former life as the Water Hashira.
And above all—his memories of his previous life. Those had to stay buried.
Yet something strange had happened. Muzan's search had been shallow, as if blocked from reaching deeper layers of his mind—like the ones holding his past life.
Giyu realized what that meant. Muzan was beginning to suspect him. This was just the first probe. Next time, it might be a direct assault.
He rose, stepping toward the window. The moonlight filtered through the bamboo grove, casting a soft silver glow across the yard.
"Shinobu, Oyakata-sama, Obanai…"
He whispered their names quietly, his gaze steady.
"No matter what happens, I won't let you down."
What he didn't know was that although Muzan's presence had retreated, it had left behind a faint mark buried deep in his memory—a trace, invisible and dormant for now.
One day, that mark would become a key.
And when that key turned, the true crisis would begin.