The pleasure district at night was still lit with dazzling lanterns. Music of strings and flutes mingled with laughter, yet beneath the glamour, dark currents flowed.
A black figure appeared silently before the gates of Kyogoku House.
It was Tomioka Giyu, now serving under Kibutsuji Muzan as the new watcher of the district, replacing Daki.
He no longer wore his deep-blue haori. Instead, he dressed in a dark-ink kimono embroidered at the collar and sleeves with faint wave patterns. His black horns were wrapped tightly under a strip of cloth, with a few strands of dark red hair falling loose. The water-like markings across his cheeks glowed faintly blue under the lanterns. His once-clear eyes had become cold, dark-blue vertical pupils—chilling and lifeless.
Since becoming a demon, Muzan's cells had not only rebuilt his body but quietly altered his nature as well. The gentle patience hidden beneath his silence had faded, leaving behind nothing but absolute calm. Even the tranquil precision of his Water Breathing had been sharpened into something unnervingly still.
"Stop right there! Who are you? Kyogoku House isn't a place you can just walk into!"
The guard at the gate barked the words arrogantly. Kyogoku House was the largest brothel in the district, run by "Omitsu," a woman with powerful connections—even officials had to treat her with respect. Her guards were long used to throwing their weight around.
Giyu didn't answer. He merely lifted his gaze.
The dark-blue slit of his pupil slid over the man's face, and an invisible pressure crashed down. The guard went rigid, his body drenched in cold sweat. His knees buckled, and he fell straight to the ground, teeth chattering as his voice died in his throat.
Without another glance, Giyu stepped past him, walking through the noisy main hall. The women who threw him flirtatious glances froze when his icy eyes met theirs. He ignored them all and headed straight toward the back room.
The door wasn't locked. He pushed it open to find a long-faced middle-aged woman in a bright red kimono counting money at a low table. She was Omitsu, the mistress of Kyogoku House.
When she looked up and saw him, she forced a smile. "Customer, if you're here for company, the upstairs rooms are that way. This isn't a place for play."
"From today, Kyogoku House belongs to me."
Giyu's voice was calm, carrying quiet authority that brooked no argument. "Hand over your ledgers and the list of informants."
"What did you just say?"
Omitsu burst out laughing, slamming a hand on the table. "You've lost your mind! Do you have any idea who backs this house? Get out while you still can, or I'll have you carried out in pieces!"
She clapped her hands sharply.
A dozen armed thugs rushed in, surrounding him. These were men she had raised herself—criminals and murderers who bullied townsfolk and lined their pockets with stolen coin.
Giyu didn't move. His expression didn't even flicker.
The moment the men lunged, his body vanished—leaving only a blur. The hem of his black kimono cut a silent arc through the air.
Slish. Crack.
A few dull thuds echoed. In seconds, every man lay sprawled on the floor, blood soaking into the tatami.
Giyu's eyes remained cold. For scum like these, even as a demon, killing them cost him nothing.
Omitsu's face drained of color. She slumped into her chair, coins spilling from her hands and scattering across the floor.
"I'll ask once more. The ledger and the list—will you hand them over?"
His dark-blue pupils reflected no mercy.
Realizing she was facing a true killer, Omitsu's hands shook violently. She fumbled through a drawer and pulled out a ledger and a folded sheet of paper, thrusting them toward him. "Here! Take them! Just—please—don't kill me!"
Giyu took them, flipping through quickly.
The ledger detailed years of illegal trade—human trafficking, bribes, and dealings with corrupt officials. The list named spies Omitsu had planted across other brothels and even within government offices.
His gaze grew colder still. Keeping someone like her alive would only breed more suffering.
"People like you are a waste of breath."
He raised his hand. A thin blade of pale-blue water formed at his fingertips—a fusion of Water Breathing and his new Blood Demon Art, far sharper than any Nichirin Sword.
The blade flashed.
Blood burst across the walls. Omitsu's head rolled from her shoulders, her wide eyes frozen in terror.
Giyu cleaned the blood from his hand, pocketed the ledger and list, and stepped back into the hall.
The terrified attendants and servants huddled at the door. He looked at them calmly. "From today, Kyogoku House is under my control. Anyone who stays will follow my rules—no forced prostitution, no dealings with corrupt officials. If you wish to leave, I won't stop you. You'll even get travel money."
The servants exchanged glances. Most chose to stay. Under Omitsu, they had lived in misery; this cold new master at least promised fair rules.
Over the following week, Giyu began taking over the rest of the pleasure district, using Kyogoku House as his base.
His first stop—Tokito House. Its mistress was no better than Omitsu, known for forcing women into the trade and torturing those who disobeyed.
Giyu said nothing. He subdued the madam's enforcers by force, bound the madam herself, and in front of all the women, read out her crimes aloud. Then he let the women decide her fate.
In the end, the furious women drove the madam out of the district, and she never dared return again.
Next was Ogimoto House. The madam there tried to collude with the local officials, hoping to use the soldiers to eliminate Giyu.
Instead, Giyu stormed straight into the government office, subduing the bribed official in moments. With cold precision, he forced the man to issue a decree forbidding any interference in the pleasure district.
With her backing gone, the madam of Ogimoto House had no choice but to surrender control.
In just seven days, the three largest brothels in the district had all fallen under Giyu's rule.
He immediately set new laws, abolished all illegal trades, paid his subordinates fair wages, and even opened a small classroom where any girl who wished could learn to read and write.
The air of the district slowly changed. The once-filthy alleys grew calmer, and even the clients, sensing the shift, reined in their arrogance.
When someone asked for his name, Giyu thought for a moment before replying, "Mushiki."
It was a name given to him by Muzan—Mushiki, the water spirit from mountain legends, a creature said to rule over rivers and floods.
Late at night, Giyu would stand atop the roof of Kyogoku House, watching the lights of the district shimmer below. The dark-blue pupils of his eyes reflected a tangled mix of emotions.
It wasn't that he didn't want to reach out to the Demon Slayer Corps. It wasn't that he didn't want them to know he was alive.
He couldn't.
Ever since becoming a demon, he could feel Muzan's presence constantly brushing against his mind—a cold shadow watching every move he made.
If he acted even slightly out of line, Muzan would destroy him in an instant. Worse, he might expose the others.
So he waited. He had no other choice but to wait.
He would bide his time—until Muzan let down his guard, until Tamayo's research on the medicine progressed, until he found a way to suppress his demonic nature and protect his comrades.
"Shinobu… Tō…"
He murmured their names softly, images flashing before his eyes—Shinobu's gentle smile, Tō practicing his sword with silent focus, Tanjiro's determined gaze, and his sister Tsutako's final words.
"Wait for me a little longer…"
The night wind brushed past, rustling his dark kimono. The cloth around his forehead fluttered slightly, revealing a glimpse of the black horn beneath.
He clenched his fist. A faint blade of water shimmered at his fingertip, then quietly faded away.
He had learned to endure—to wait for light while standing in darkness.
Each day, Giyu gathered information from the district and sent it to the messengers of Infinity Castle using the secret method Muzan had assigned him.
But in secret, he was gathering intelligence on Muzan—tracking the movements of Infinity Castle's messengers, the progress of Muzan's search for the Blue Spider Lily, and even subtly altering reports so Muzan would lose track of the Demon Slayer Corps.
He was walking a tightrope, balancing between the mask of Muzan's obedient servant and the quiet strength of a man who refused to abandon his humanity.
His coldness had become his armor. His calm had become his weapon.
And in his own silent way, he was preparing the path for the final battle.
The lights of the district still burned bright—but none of that light reached the deep, dark blue in Giyu's eyes.