The morning after, Aozuki Castle lay wrapped in silence. From the garden of Tsukishiro no Ma, the early summer sunlight filtered through in pale, golden streams. When Masumi Yoizuki opened her eyes, she rose and stood by the window. The previous night's audience with the castle lord lingered still in her mind, a vivid impression that would not fade. (The library...) A world of permitted books. Those words alone remained in Masumi's chest as living hope. Knowledge—the sole weapon by which she, a person displaced from the present world, might survive in this castle. And that source lay somewhere deep within these walls. Guided by Yukie, the senior attendant, Masumi made her way toward the inner citadel. The same corridors as yesterday. Yet today, the landscape appeared transformed. The sunlight falling across the stone pavement seemed more vivid, more acute. The portraits of successive castle lords seemed to regard her with evaluating eyes—no, that was merely her imagination. Her nerves, nothing more. Yukie's footsteps turned in a direction different from the day before. Deeper into the inner citadel. The corridors grew narrower, the light diminished with each step. "The library lies in the deepest part of the castle. No one approaches it without the castle lord's permission." Yukie's voice carried an unusual weight. The significance of this place seemed to seep through her words, coloring them with reverence and caution. At last, a single large door appeared. A thick wooden door. Upon it, a single Chinese character was carved: 書—"book." When Masumi's fingers touched it, the warmth of the wood transmitted itself to her fingertips, a gentle heat that spoke of age and care. "Shall I open it for you?" Yukie asked for confirmation. Masumi nodded. The door swung open in silence. In that moment, Masumi's breath caught. A library. Bookshelves that reached to the ceiling filled the entire room. Not one or two, but dozens. Hundreds, perhaps. Arranged in a labyrinth of vertical and horizontal lines. Mountains of books. A sea of books. An entire world of books existed here. Sunlight entered only from high windows, illuminating particles of dust that drifted like tiny stars. In that light, books that had slumbered for centuries seemed to breathe quietly, as though still alive. (This is...) Masumi stepped forward, then forward again. Even the sound of her footsteps on the floorboards seemed to transform into music within this space. She approached a shelf and examined the spines. *The Military History of Aozuki Domain.* *The Complete Medical Arts of Ashihara.* *The Great Compendium of Strategy.* *Poisons and Their Antidotes.* Each title was inscribed in gold leaf. She withdrew *The Military History of Aozuki Domain.* It was thick, heavy. When she opened the pages carefully, the scent of old paper tickled her nose—a faint, slightly sour aroma. The smell of wood and time itself. The pages bore handwritten characters in neat rows. Two hundred years of history from the domain's founding. Wars. Population counts. Harvest yields. All recorded with the precision of data. (This world has a culture of record-keeping too.) Masumi drew book after book from the shelves. *The Complete Medical Arts* contained the medical knowledge of this era. Types of medicinal herbs. Their toxicity. Treatment methods. Primitive compared to modern medicine, yet written with remarkable detail. (Herbal remedies... with modern medical knowledge, there might be improvements possible.) Masumi became absorbed. Time ceased to exist. She opened book after book, turned page after page, traced character after character. The past of Aozuki Domain. The medical practices of this world. The evolution of strategy. All of it held potential as a weapon for her survival. The light from the window shifted. Morning became noon. Noon became afternoon. Masumi did not notice. She simply continued reading, consuming knowledge like hunger itself. Then it came. A faint presence behind her. Masumi turned. The castle lord stood there in silence. Jet-black hair. Eyes deep and cold as obsidian. A small scar above his right eyebrow. All of it registered in her vision in an instant. The castle lord's expression revealed nothing of his thoughts. An icy stillness emanated from him. Masumi's body went rigid. "You are different." The castle lord spoke in a low voice. Whether it was praise or criticism, his tone offered no clarity. "...I apologize." Masumi bowed her head instinctively. "I have disturbed the library." The castle lord said nothing. He only gazed at the book in her hands. *Poisons and Their Antidotes.* (I made a mistake. I never expected the castle lord to come...) Would reading that particular book invite suspicion? Masumi found herself forced into a split-second judgment. Yet to dissemble here would be dangerous. This castle lord was not someone easily deceived. "I wish to learn about poisons." Masumi spoke with honesty. "With modern medical knowledge, understanding of toxicity would deepen. That might serve to protect the health of the domain's people." The castle lord's gaze shifted. He looked directly at her. "...Modern medical knowledge." He repeated the phrase. There was something in his tone—as though he had grasped something significant. "Do you possess knowledge that does not exist in this world?" Masumi's heart quickened. This question was dangerous. Yet she responded with composure. "The mark on my left wrist is said to be the proof of one displaced from the present world. I... came from another world." By speaking this truth outright, Masumi made her gamble. Confession, she believed, would generate trust more readily than concealment. At least, that was how it worked in novels. Whether reality would mirror fiction remained unknown. The castle lord remained silent for a long time. (It's over... I'll be executed...) Fear passed through Masumi's mind. Yet the castle lord did nothing. He merely narrowed his brows slightly. "Interesting." That single word changed everything. The castle lord walked slowly through the library. He withdrew another book from a shelf. *The Great Compendium of Strategy.* "This library is my refuge. The accumulated knowledge of successive castle lords dwells here. If you, too, possess knowledge from another world..." He turned to look at her. "Come whenever you wish. No permission is required. Use this place as much as you desire." Those words carried meaning far deeper than a mere promise. The loneliest person in this castle was offering a shared space to another solitary soul. Masumi did not know what to say. "...Thank you." It was all she could manage. The castle lord said nothing more. He departed the library. His retreating figure seemed, somehow, faintly weary. Masumi stood alone. In the silence of the library. (What is he really thinking...) That question took root in her heart and began to grow. --- That night, when Masumi returned to Tsukishiro no Ma, an unexpected scene awaited her. A summons had come from the inner quarters. The three other concubines were waiting for her. The room was dimly lit, lit only by oil lamps. The faces of the three women floated in that light. Among them, the coldest gaze came from Ayaka Sanno. Twenty years old. Eyes that spoke of a strong will. Long, carefully maintained black hair. As a relative of the castle lord, her position was secure. And upon her face was written unmistakable jealousy. "I hear the castle lord has granted you access to the library." Ayaka's voice was clear as a bell. Yet beneath that clarity lay hidden poison. Masumi sensed it. "Yes. I have been given permission." Masumi responded with courtesy. "I am fond of books, so..." "We have been here for years, yet you, who have only just arrived, receive such special consideration." The first concubine—the senior among them—spoke in a low voice. Her tone carried unmistakable anger. "The castle lord rarely does such things. Yet for you alone..." The third concubine also fixed her gaze upon Masumi. Her face mingled wariness with curiosity. "Is there a political intention behind this? Or perhaps... does the castle lord expect something of you?" Three questions—or rather, three accusations—were directed at Masumi. She responded with calm and courtesy. "I apologize. The castle lord's thoughts are beyond my comprehension. I simply love books. There is no deeper intention." Her answer was truthful. Yet whether the three women believed it was another matter entirely. Ayaka rose to her feet and approached Masumi. The distance between them was deliberately closed. "The castle lord's heart is closed to everyone. Even if you believe yourself special, it is futile. The castle lord does not trust in human hearts to begin with." There was something desperate hidden in those words. Ayaka herself had likely experienced rejection from the castle lord many times. "That is not..." Masumi responded gently. "Perhaps the castle lord granted permission out of respect for one who seeks knowledge. Not because of gender or position, but for the pursuit of understanding itself." It was Masumi's genuine intuition. The castle lord was not seeing her as a concubine, but as one displaced from the present world. As a being possessing knowledge from another realm. There was something profound in that distinction. Yet her words did not ease the three women's anxiety. If anything, they seemed to deepen it. "Be careful." Ayaka whispered near Masumi's ear. "To be favored by the castle lord is dangerous in this castle. You will gain enemies." With those words left behind, the three departed. Masumi stood alone. In the dimness of Tsukishiro no Ma. (What a troublesome world this is...) A sigh escaped naturally. Modern Japan too had its relational complexities. Yet the complexity within these castle walls seemed bound to matters of life and death. To be favored by the castle lord was simultaneously to invite the enmity of the other concubines. The factional struggles among the concubines. She had entered that arena as a new participant. Masumi felt the weight of it acutely. (The castle lord is lonely. He trusts no one. That's why he retreats to the library.) Such thoughts took root in the depths of her heart. And at the same time, Masumi understood something else. (It will only become more complicated from here. My survival strategy in this castle...) Beyond the window, the moon shone white and luminous. In that light, Masumi faced a new and complex reality.