The guild's archive always smelled faintly of dust. The moment his lunch break began, Tsubaki Shinji closed the archive door and pulled a bundle of ruin reports from the second shelf of the cabinet. Three reference books in old map format. He spread them across the desk alongside the notes he'd copied the previous night from the stone wall patterns—geometric fragments crammed onto thin paper. Something had become clear by last night. The three-way intersection on the first level had different spacing between the wall grooves. The left and right branches were evenly spaced, regular as wood grain on a desk. But the central passage alone had grooves that gradually narrowed. According to an old ruin report he'd obtained from Akotsubo—the lamp crystal shop on the main street—Volkis-period architecture used combinations of floor color and wall grooves to indicate direction of travel. (So that intersection isn't a trap. It's a sign.) Shinji ran his pencil across the page. He drew a small diagram on a fresh page of his conquest notebook. Arrows. Numbers for each intersection. Light gray floor meant left. Blackish stone tiles meant right. The tighter grooves in the center passage marked the descent to the lower level— He finished after using half his meal time. Shinji closed the notebook and put the remaining hard bread in his mouth. Stale. He'd bought it three days ago. He washed it down with water from his flask while surveying the archive shelves again. The arrangement seemed different from his last visit. It might have been his imagination. The shelves were dim, lit only by natural light from the window. But Shinji was meticulous with documents. Two books that should have been in numerical order were slightly misaligned—no, their spines were facing the wrong direction. The kind of careless replacement someone makes in a hurry after consulting something. (Who touched these?) His instincts as a clerical worker activated. Shinji quietly returned the books to their proper positions, confirmed the feel with his fingertips, then left the archive. —— Work ended at dusk. The stone tiles of the main street reflected the sunset, glowing orange. Seraphim Yulia came running through it. Her short blonde bob swayed, and the feather ornaments on her earrings glinted. Even from a distance, her entire body radiated the determination of "we're going today." "Master! Let's go!" Yulia called. At the entrance to Shinji's home garden, Yulia was already stepping forward. Her foot was on the edge of the board-enclosed hole, about to descend. Shinji silently held out his notebook. Yulia took it and flipped through the pages. Seconds later, she looked up. "...This is all text, isn't it?" Yulia asked. "There are diagrams too," Shinji replied. "Where?" Yulia asked. "Next page," Shinji said. Yulia turned the page. She stared. And stared. And kept staring. "Master," Yulia said. "Yes," Shinji answered. "I don't think this qualifies as a diagram," Yulia said. "There are arrows and numbers. It's a perfectly legitimate diagram," Shinji said. "There's no scale, the arrows overlap in three places, and what is this square supposed to be?" Yulia asked. "A three-way intersection," Shinji said. "A three-way intersection is usually drawn like this," Yulia said. She traced a shape on the ground with her finger. Shinji thought for a moment, then added a correction to that section of the notebook. Yulia leaned in to look. She fell silent again. "Master, even if you fix the square, it doesn't solve the fundamental problem," Yulia said. "If you follow the numbers in order, you'll understand. I'll explain," Shinji said. "On site?" Yulia asked. "On site," Shinji confirmed. For the next five minutes, the two debated the notebook diagram in front of the garden hole. Every time Yulia asked "Is the arrow here pointing right or left?" Shinji answered "You'll understand from context," and Yulia replied "I don't understand." Eventually, Yulia declared "Master, let's descend. I'll learn as we go," and took the exploration lamp. Shinji put away the corrected notebook and descended first. —— The first level's corridor was a stone passageway branching left and right. The lamp's pale blue light reacted to the wall patterns, making them glow faintly. For Shinji, it was a familiar sight after four days of exploration, but Yulia looked around carefully with each step. "It's cold here," Yulia said. "About twelve meters underground. Two or three degrees cooler than the surface," Shinji replied. "The wall patterns are glowing properly. They're reacting to the lamp, aren't they?" Yulia said. "They seem to contain trace amounts of lamp crystals. Whether they're residual or structural, I haven't determined yet," Shinji said. They reached the three-way intersection. Yulia stopped and checked each direction in turn. "Which way?" Yulia asked. "Look at the floor," Shinji said. Yulia looked down. The left branch had a light gray floor. The right branch was a dull black. The central passage had a step down. "Left. The lighter floor is the safe horizontal route, and the central step is the descent to the lower level. Today we go down," Shinji said. "...I see. So that's why the notebook had information about colors. I didn't feel like reading all that text though," Yulia said. "Please read all of it," Shinji said. "Master, I was being positive," Yulia said. They passed through two more intersections. Following Shinji's guidance, Yulia never rushed ahead. She walked quietly beside him as he confirmed the wall grooves with his fingers. "You're meeting the second condition today," Shinji said. The second rule he'd given Yulia that night—"Don't walk ahead on your own" and "Don't attack without orders." "That one failure is past its expiration date," Yulia said. She looked slightly embarrassed as she faced forward. Her feather earrings swayed gently in the lamp's light. Shinji said nothing. He simply stepped onto the next descent. The passage to the second level had steeper stone steps than the first. The treads were polished so smooth that Shinji descended carefully, confirming the stone's texture with each step. Yulia followed from above, holding the exploration lamp. Beyond the final step, the ceiling rose higher. The first level's ceiling had pressed down oppressively, but here it was over two meters high. The density of geometric patterns on the walls had clearly increased, and they glowed faintly in response to Shinji's lamp. Much stronger than the first level. "Wow," Yulia said softly. It was a sound somewhere between admiration and surprise. "Second level," Shinji said. "I know. But this is... amazing," Yulia said. The two stood in that light for a moment. Their footsteps had stopped. The smell of stone mixed with something faintly sweet—neither earth nor grass—hung in the air. It was a space with an unusual sense of openness, making one forget they were underground. A large chamber appeared ahead. Shinji entered first. In that instant, a sound came from a wall recess. A low mechanical hum. Stone grinding against stone. Shinji and Yulia both stepped back simultaneously. A shape slowly emerged in the lamp's light. A stone humanoid figure over two meters tall. Lamp crystals were embedded throughout, glowing faintly. Its arms were as thick as Shinji's torso. Its face had eye-like indentations but no expression. It approached with heavy footsteps, one after another. Not the sudden charge of a Gorg Worm. A steady, deliberate pace. (One hit and it's over.) Shinji's instinct was immediate. If struck by that arm, bones would be the least of his concerns. He checked Yulia's face. Rather than fear, her eyes showed fighting spirit. Her emerald green eyes measured the stone statue. "How should we move?" Yulia asked. "We observe. First, we don't move," Shinji said. The two pressed themselves against the chamber's edge. The stone statue reached the center of the room. It continued moving at a constant speed. Shinji's eyes narrowed. The back. The front crystals glowed brightly. But at the center of its back, around where shoulder blades would be, one crystal moved differently. Its light pulsed stronger and weaker in a regular rhythm. Like a heartbeat. Like breathing. Its movement was out of sync with the other crystals. (There. That's it.) Shinji pulled Yulia's arm and whispered into her ear, keeping his voice as small as possible—they still didn't know if the statue would react to sound. "The center of its back. Do you see the crystal with fluctuating light? That's likely the weak point. You draw its attention from the front and make it turn. I'll circle behind," Shinji said. "Understood. I'll use lamp crystal body enhancement," Yulia said. "Maintain a safety margin. Don't get so close it's reckless," Shinji said. "Master, I'm E-rank but I'm confident in my speed," Yulia said. "Right now, I trust that E-rank confidence most. Let's go," Shinji said. Yulia moved. With lamp sensitivity of thirty-two, her body enhancement made her movements visibly faster. She kicked off the chamber floor and dove at the statue's front. The statue sensed her movement and swung its arm. Yulia slid backward. The statue began to turn. Shinji ran in the opposite direction. The statue's turning speed was faster than expected. As Shinji tried to circle behind, the statue's body rotated to face him. "Wait, it's fast!" Shinji called out. His voice escaped. The statue started to turn toward Shinji, then immediately faced Yulia again. Yulia kept running, drawing the statue's attention. "It got faster, didn't it, Master!" Yulia called cheerfully while running. She was praising him mid-combat—a statement specialized in exactly that. (This isn't the time for praise!) Shinji withdrew to cover and observed the statue's movement again. Constant turning speed. The wider Yulia moved, the wider the statue turned. If they could narrow the turning radius— "Yulia! Lure the statue toward the wall! Narrow its turning space!" Shinji called. "Got it!" Yulia replied. Yulia's movement changed. Instead of circling the chamber widely, she gradually herded the statue toward the wall. As the statue approached the wall, its available turning angle narrowed. Shinji tracked its movements with his eyes, timing his approach. Now. Shinji ran behind the statue. He gripped the wooden mallet—the one he'd pulled from the storage shed the day after writing "need blunt weapon" on page three of his conquest notebook—with both hands. He confirmed the position of the pulsing crystal on the statue's back. The moment the crystal flared bright, he swung with all his strength. A dull thud. Then a crack. A fracture ran through the crystal. Again. This time at a slightly different angle. Thud. Splinter. The crystal shattered. The statue's entire body flared brilliantly for an instant. Then, slowly, the light faded. Its arms stopped. Its feet stopped. It went silent, standing motionless. The mechanical hum vanished, and silence fell over the chamber. Shinji lowered the mallet, breathing hard. Yulia ran over. She held the lamp up high, raising her right hand. "We did it!" Yulia said. Her eyes asked for a high-five. Shinji hesitated slightly. There was a moment of disconnect between himself as a forty-five-year-old clerical worker and himself tonight. Still, he raised his right hand. It met Yulia's with a crisp sound. "Well done," Shinji said. "Well done isn't it! That was incredible! Master, your movements were perfect!" Yulia said. "It was only possible because of your guidance. You made the decision to narrow the turning radius before I even told you to," Shinji said. "Huh?" Yulia's eyes widened slightly. Shinji continued. "Your movement toward the wall changed before I gave the order. You must have assessed the situation and decided," Shinji said. "...Well, kind of," Yulia said. "Being able to reach the right answer