A hoarse crow's call echoed through the silent, pitch-black forest. A few birds burst from the trees, their dark silhouettes flashing across the full moon as the leaves rustled softly.
Muzan returned to his residence while the night was still deep. As he entered, a mirror on the side reflected his mouth, still stained with fresh blood. He took out a handkerchief and wiped it clean.
Five days ago, he had died suddenly—and transmigrated. When his soul entered this world, the "impact" was so strong that Muzan's soul scattered, causing him to faint. He had successfully taken over this body and, in the process, absorbed the soul of the so-called Scum Boss, along with all his memories.
The details didn't matter. What mattered was the undeniable truth: staying up late really could kill you.
Before this transmigration, the Scum Boss had turned a doctor—one who desperately wanted to live—into a demon, then temporarily stayed in the doctor's home.
When Muzan returned, the doctor, Ryuzawa Yoshitsugu, hurriedly bowed and respectfully greeted him as "Master." Once Muzan entered his room, the doctor returned to work.
Ryuzawa Yoshitsugu had been chosen by the original Muzan for his excellent medical skills. His personality, however, was far more decent than the Scum Boss's—despite becoming a demon, he rarely preyed on humans and instead targeted the worst criminals. Sometimes, he even saved people.
The original Scum Boss had found this attitude intolerable. If not for Ryuzawa's skills, he would have killed him long ago. The current Muzan, however, found the man much more likable.
Back in his room, Muzan pulled a book from the shelf, sat cross-legged on the floor, and began reading. He never expected that after transmigrating, he'd be able to sit still and study—especially theoretical medical texts he used to find painfully dull.
Maybe it was the influence of the original Muzan's memories… or maybe this era was just unbearably boring. It was the year 1467, the Sengoku period of the island nation. With no modern entertainment, he planned to survive quietly until mobile phones were invented. Without something to read, boredom might actually kill him.
The sky slowly brightened. Sunlight filtered through the paper windows, making Muzan's skin burn faintly. He draped a black cloth over the light and kept reading. Thankfully, his demon vision allowed him to see clearly even in total darkness.
Meanwhile, Ryuzawa Yoshitsugu was treating patients as usual, all while using Muzan's blood in his attempts to overcome the sun. But Muzan already knew his thoughts: I can't do it. I really can't!
He was just a doctor—an exceptionally skilled one, yes—but helping a demon conquer the sun was far beyond his abilities.
By the time Muzan turned the last page of the thick volume in his hands, the white paper beside him was already covered in neat, tiny notes. He closed the book, put it back, stored his notes, and stood.
The door to the outer room was slightly ajar. Pushing it open, he saw Ryuzawa hunched over a thick tome, his own papers covered in messy writing. His expression was one of pure frustration—much like a student stuck on the final problem of a college entrance exam.
He was still desperately trying to meet the Scum Boss's impossible demand, clinging to the hope that he wouldn't be killed for being useless.
When he noticed Muzan approaching, Ryuzawa stiffened instantly, swallowing hard as he stood and bowed.
Muzan, used to such reactions, picked up the book on the table. "If you can't do it, don't bother."
Ryuzawa's already pale face drained of color. Sweat broke out on his forehead. "Ma… Master! I can do it!"
Muzan closed the book with a sigh. This is just fear of being thrown away.
"I won't kill you. Just keep improving your medical skills," he said before turning to leave with the book. That had been his real purpose here anyway.
Thump, thump.
A soft knock came from the outer door. Muzan's interest was piqued. He pulled over a stool and sat to the side.
Ryuzawa glanced at him before calling out, "Come in."
Three people in Demon Slayer Corps uniforms entered quickly, two of them supporting the third. The injured man's waist was soaked with blood, and the other two bore cuts and torn clothing.
Ryuzawa froze, instinctively wanting to flee. But Muzan's voice echoed in his mind: Calm down. They're here for treatment.
Muzan himself was briefly surprised, but since they had knocked and seemed weak enough not to recognize demons on sight, he relaxed. The scene was amusing—Demon Slayers coming to a demon for help.
Kibutsuji Muzan possessed five brains and seven hearts. The extra brains granted him not only enhanced intelligence but the ability to monitor his demons. Since transmigrating, however, he rarely bothered.
Just to be sure, he checked: None of the nearby demons have fought the Corps, right?
With Muzan's reassurance, Ryuzawa allowed them to lay the patient on a bed and began examining the wounds—though his face still twisted with hesitation.
He didn't dare save them. A doctor's heart might be compassionate, but self-preservation came first.
Save him, Muzan ordered in his mind.
Ryuzawa relaxed slightly and, following the cue, asked casually, "How did this happen?"
The youngest Demon Slayer leaned his Nichirin Blade against the bed and slumped into a chair. "Bandits! Damn it, what trash!" he spat angrily.
The other grumbled, "And they got away. Tsk."
Ryuzawa treated the wound while murmuring, "Ah, this chaotic world…" Then he added, "Try not to go out at night. Someone nearby was taken by a demon again."
Muzan, listening, told him afterward, "Don't worry. They were talking about a different demon."
Although he hadn't created many demons, the area had a decent concentration, all confined to the Edo region.
"Also," Muzan added casually, "tonight, deal with those bandits. Bring me back one."