Her eyelids were heavy. 　Yoizuki Masumi felt herself being drawn up from the depths of consciousness, and slowly opened her eyes. She could see the ceiling. But it was not a ceiling she recognized. 　White plaster. An old-fashioned beam. Soft light filtered through the shoji screen. Morning light, perhaps. Or something else entirely. Her mind felt thick with fog, thinking difficult. "A... ah..." 　As she tried to speak, Masumi became aware of something wrong with her body. She couldn't move. No—that wasn't quite right. The intention to move wasn't reaching her limbs. Her entire body felt strangely paralyzed. Panic pierced through her chest. 　What had happened? 　A traffic accident. Yes. Omotesando in Tokyo. On the way back from work. That moment— 　And then, memory flooded back. 　A deafening roar. Headlights. Then, impact. She had been hit by a car. Certainly. She should have died. Yet here she was. Alive. "A... a..." 　Masumi forced strength into her body with desperate effort. Her fingers moved. Her feet moved. Gradually, her entire body began to obey her commands. Slowly, carefully, she raised her upper body. 　Black hair that fell to her knees. She felt its weight for the first time. Her own hair had been short. "What?" 　Masumi stared at her hands. White arms. Long, slender fingers. These hands were hers, and yet they were not. 　She dragged her body toward a lacquered mirror stand placed in the corner of the room. Her palms touched the tatami mat. A rough texture. A faint grassy scent tickled her nose. This sensation too was entirely new. 　When she sat before the mirror, Masumi caught her breath involuntarily. 　The face reflected there was certainly her own. Deep brown eyes. Refined features. But this woman—her long black hair was arranged carefully, pinned up with precision. She was dressed in a pale indigo kimono, a white obi cinching her slender waist. "What? What is this?" 　Masumi lifted the sleeve of the kimono. The fabric was fine, pleasant to the touch. When she looked at her left wrist, a faint pattern floated there—a thin, silvery marking. Was it something she was born with, or some kind of seal? 　A headache struck. Sharp pain pierced her temple. "Ah..." 　Masumi clutched her head. In that instant, memories came flooding like a torrent. 　Twenty-four years. Twenty-four years in Tokyo. Her parents' faces. High school friends. A college romance. Days after employment. Sales work. Tension with clients. Harassment from her boss. Bullying. A breakup. Everything. Everything returned as vividly as reality itself. 　But at the same time, new memories flowed in. 　Another world. An era like the Sengoku period, a time of warfare. Ashihara no Kuni—that was what this country was called, where feudal lords competed for dominance. Aozuki Domain. A territory in the mountainous north, a battlefield. Aozuki Castle there. 　And she was— "A concubine..." 　The whispered word echoed hollowly through the room. She had just entered the castle as a concubine. The fourth concubine of the Aozuki Castle lord. Her origins unknown. No questions asked. She had simply entered. 　Why? 　That question brought no answer. The memory was clear, yet the reason remained blank. 　But other information was vivid. 　Genseiwatari—one who had been reborn in Ashihara no Kuni from another world. Such beings appeared in records perhaps once or twice per century. Most were executed as supernatural abominations. "Executed?" 　Masumi's spine went cold. She was genseiwatari. Her memories of her previous life remained perfectly clear. This was reason enough for execution. Certainly. 　She looked out the window. Stone walls. Beyond them, a row of samurai residences. Burnt-brown roofs. Wooden fences. And in the distance, a soaring keep. All of it was not Tokyo. This was Ashihara no Kuni, a castle town in an era like the Sengoku period. 　Masumi stared at the landscape without blinking. "It's real. It's really..." 　Her voice wouldn't come. Her body trembled. Was this a nightmare? Or reality? 　Then, footsteps sounded from beyond the shoji screen. Someone walked the corridor. "Concubine-sama, how are you feeling?" 　The sliding door opened quietly. A woman. Mid-twenties, an unfamiliar face. Dressed in a kimono, her hair arranged in black. A lady-in-waiting who served the castle, surely. 　Masumi took a deep breath. Suppress the panic. Stay calm. Now, she had to be calm. "I am merely a little tired." 　Her tone was composed. Her sales pitch from her previous life proved useful now. Don't let the other person sense your anxiety. Yes, as if you truly understood everything. "I understand. Then, welcome to Aozuki Castle. I am Yukiie, a lady-in-waiting." 　The woman bowed. Her movements were graceful, clearly educated. Yet in her eyes lingered a faint wariness. A natural caution toward a new concubine. "Thank you. Could you leave me alone for a while?" "Of course. If you need anything, please call out to the corridor." 　The woman departed. Silence returned. Masumi was alone again. 　She looked around the room. Eight tatami mats. This room, called Tsukishiro no Ma, was the smallest quarters for a concubine. The furnishings were modest. In other words, her status was low. A newcomer, of unknown origin, a concubine with no political value. 　That awareness brought, paradoxically, a measure of relief. "So for now, I won't draw attention." 　She noticed a lacquered document box placed in the corner. When she opened the lid, a single letter lay inside. 'Precepts for a Concubine's Entry' 　As she read, astonishing information was recorded. 　The composition of Aozuki Domain. The Aozuki family crest. The ranks of the concubines. The first was the daughter of a southern daimyo. The second was a woman of noble blood from a powerful clan in the capital. The third was a distant relative of the castle lord. The fourth was of unknown origin. 　She was the lowest. 　And there was an even more terrifying passage. 'Genseiwatari—one who has been reborn in Ashihara no Kuni from another world. Should their true nature be discovered, they shall be executed as a supernatural abomination.' 　Masumi's hands trembled. "I must never be discovered." 　Those words felt like a curse upon herself. 　At dusk, the lady-in-waiting brought food again. The portions were few, but arranged with care. "The castle lord is attending to his duties in the inner keep today. Your first audience with him shall be tomorrow evening, we are told." "The Three Nights Oath, then." "Indeed. A new concubine shall meet with the castle lord over three nights. On the third night, the castle lord shall render his judgment." 　As Masumi listened to the explanation, she deduced the purpose of this custom. It was a period to determine whether the new concubine pleased the castle lord, whether she held political value. Over three nights, she would meet with him each evening, and based on his demeanor and judgment, her position within the castle would be decided. Or she might be cast out. The castle lord held absolute power over life and death. "So it begins tomorrow. My fate is decided on the third night." 　The lady-in-waiting nodded. "Indeed. Please bear in mind that the castle lord's judgment may be anything, depending on his mood." 　Beneath those words lay an implicit warning. Be cautious. Be vigilant. Pleasing the castle lord was the condition for survival in this castle. "Is there anything you wish to know about the castle lord?" 　Masumi picked up her chopsticks. She was careful with her grip. Her previous experience served her well. Fingers positioned correctly, angles precise. "What manner of person is the castle lord?" 　The lady-in-waiting's expression changed. Respect and fear mingled there. "The castle lord is called the Unscathed Demon General. Though he has experienced dozens of battles, it is said he has never once been wounded." "Never... been wounded?" "Indeed. For this reason, both allies and enemies fear him as a demon. Moreover, he rarely shows emotion, and is said to be a man of cold severity." 　Masumi sighed inwardly. "Ah, a typical cold character. I've seen plenty in novels." 　The words didn't leave her lips. But the thought continued. Cold. Emotionless. Never wounded. All of it was a stereotype she'd encountered countless times in fiction. That such a thing existed in reality was ironic indeed. "What are the other concubines like?" "The first concubine is the daughter of a southern daimyo. She is strong-willed and skilled at reading the castle lord's moods. The second concubine came from the capital of Kyoto and is an elegant woman. The third concubine is a relative of the castle lord, so her position within the castle is secure." 　In other words, all the other concubines possessed political value. She was the least valuable among them. "I understand." 　Masumi continued eating. Rice. Salty pickled vegetables. Thin miso soup. All of it was food from this era. 　And at the same time, she realized something. "Medical knowledge. Economic systems. Military tactics. All of it might be useful." 　How much value would the knowledge she'd gained in modern Japan hold in this era? Medicine was underdeveloped here. Economics too. Military strategy. All of it could become her strength. "I have weapons." 　That realization brought Masumi hope for the first time. She should have died for certain, yet she lived. And she possessed tools for survival. 　At night, she stepped into the garden of Tsukishiro no Ma. The moon had risen. Its white, gentle light illuminated the castle grounds. 　Masumi stood in that light. "Mother... Father..." 　The names she whispered belonged to people she would never see again. Her parents' faces. Her younger sister's face. Her friends' faces. All of it had become the past. 　Tears came. 　But Masumi did not linger with them. In seconds, she composed herself. "There's no time for tears. I will survive here. And someday, I will find a way home." 　With each word, her resolve strengthened. 　Tomorrow, the 'Three Nights Oath' would begin. Her audience with the castle lord. The reactions of the other concubines. All of it would determine her fate. "I am Yoizuki Masumi. With the observation and adaptability I cultivated over twenty-four years in my previous life, I will survive this world." 　Beneath the moonlight, Masumi made this quiet vow. 　She returned to Tsukishiro no Ma and lay down on the prepared bed. But sleep would not come. She stared at the ceiling, waiting for dawn. 　The beginning of a new life. It was already here.