Stone wall construction had resumed before dawn. The sky over the ash plains was still a deep indigo, with only the eastern ridge faintly whitening. The continuation of work from yesterday—Ren reinforcing the outer foundation and Koichi assembling the wall materials for the first section—was the first task of this morning. He examined each piece of scrap stone one by one, selecting those without cracks and stacking them. His hands were cold. The sand was gritty. Yet as long as he kept moving, he didn't have to think too much—Koichi had confirmed this again last night. "Koichi." Ren's voice fell into the silence of the wasteland. Koichi turned around. Golden eyes looked directly at him. Red streaks mixed through black hair appeared dull in the pale light before dawn. In Ren's hands was not a design notebook, but some kind of cloth. "I've completed a patrol of the southern perimeter." Koichi set down his stone. Ren knelt and pointed at the ground. Multiple footprints remained in the ash plains' sand. Not just human footprints—hoof marks were mixed among them. Traces of a group leading horses or large beasts similar to them, passing in an arc along the south side of Akatsugu. "Look at the spacing." Koichi crouched to examine the footprints. The distance between steps was wide. Even with heavy equipment, the stride didn't break—the gait of a trained person. The depth of the footprints was uniform too, neither hurried nor fatigued—rather, the traces of someone moving while observing calmly. "Not travelers." "Yes. A group with combat equipment deliberately circled Akatsugu at a distance. I believe they were observing the number and arrangement of buildings while maintaining their distance." Ren continued, explaining that these were scouts of the armed forces controlling the mining regions to the south—the Kouga-shu, a military faction that monopolized ore sales as their funding source and controlled surrounding settlements. Koichi and Serika had heard that name before. It was a force known throughout this ash plains region. Ren hadn't stated it outright, but his tone of voice made it clear. Then came the sound of water-blue hair rushing through the morning light. "You two are up early! I just got here too—wait, why do you both look so serious?" Serika saw the footprints and her expression changed. Her pale violet eyes traced the ground, then alternated between looking at Ren and Koichi. "...Could it be that some traveling merchant or someone passed through in the dead of night or something?" A moment of silence. Ren silently pointed to the hoof marks, particularly the ones pressed deepest into the ground. The way a merchant's horse laden with cargo sinks into the earth differs from a mounted war horse. "...Right," Serika said quietly. Usually, Serika's optimistic remark would ease the atmosphere a little. In fact, she might have intended it that way. But this time, the three of them didn't have the space to receive it. A morning bird called in the distance. Its voice was low and dry. Koichi had taken out his notebook. He traced through the remaining construction phases with his finger. Sections completed by yesterday, sections that needed to be finished today, material inventory. Looking at the numbers, the fear transformed into a design problem. That transformation was what Koichi needed right now. "Today, we'll complete two watchtowers simultaneously." Ren and Serika exchanged glances. --- Work proceeded under wartime-like tension. Ren organized the sequence of tasks, adjusting the flow of residents carrying building materials so it wouldn't intersect with the wall construction. True to his meticulous nature, he wrote out each phase in detail and assigned priorities. "This section first, then here next, the ladders in two groups"—his words were brief, but complete. Watching the surrounding residents naturally follow his instructions, Koichi felt slightly reassured. He couldn't make these kinds of adjustments alone. Serika was tasked with locating scrap materials through mana detection. By faintly sensing mana—invisible particles drifting in the atmosphere—she could read the density differences of stone and wood buried under sand and rubble. Each time the faint light at her fingertips indicated stone beneath the sand, she'd call out "Here!" Her accuracy was high. Thanks to her, the scrap recovery speed had doubled compared to yesterday. Koichi's Building Master accelerated construction. He placed his hand on scrap stone and poured mana into it. Stone aligned with stone, wood fixed at precise angles. Once the blessing effect took hold, completed structures became more durable than ordinary building materials—the outer wall of Ash Wall Fortress should have possessed twice the strength of a normal stone wall. By the time the foundation of the first watchtower was assembled and Koichi began stacking the upper wall materials, sweat began beading on his forehead. Even though the morning air was still cold. Ren noticed and quietly placed a vessel of water beside the ladder. He said nothing. Only his gaze conveyed "drink." Koichi saw it from the corner of his eye, but didn't descend the ladder. The vessel remained on the sand. Serika looked up at Koichi, starting to say something. Her mouth opened. But closed. Opened again—closed again. The density of Koichi's concentration left no opening for her voice. Serika, who would normally laugh and interject "you don't need that much precision!" couldn't produce those words this time. She wanted to voice her worry, but couldn't find the outlet. Unable to laugh, yet somehow laughing—Serika herself seemed most troubled by that absurdity. The first watchtower was completed. The moment the blessing effect took hold, the stone materials of the watchtower glowed faintly warm. Confirming this, Koichi moved to the second. --- The problem occurred during the upper section assembly of the second watchtower. Koichi placed his hand on a piece of scrap stone. He tried to pour mana into it. Nothing happened. He pressed his palm against the stone again. Concentrated his consciousness. Tried to sense the flow of mana. It wasn't there. The Building Master didn't respond. A sensation of emptiness in his hand—that was all. (This is wrong.) Confused, he tried to verify his memories from this morning. Which scrap materials he'd used in what order. Which section of the wall he'd reinforced. How many stones he'd stacked in the first watchtower— It was hazy. The outline of his memories had become vague, as if shrouded in mist. Only vague fragments floated up and disappeared. The tactile sensation of the wall he'd stacked this morning remained oddly vivid in his palms, yet he couldn't connect it to which task or which stage of work it had been. Mana intoxication—a symptom that occurred when mana was consumed excessively. Mild cases brought headaches and nausea; severe cases led to loss of consciousness and damage to the mana circuits. Koichi had tasted it slightly on that day when he'd first attempted major construction, but this was far worse than that haze. He gripped the ladder's support beam with both hands. He was standing. But that was all. A voice came from the ground. Serika's voice—he couldn't make out what she was saying, but her pitch had changed. The next moment, the ladder swayed. Serika was climbing up. Before any conscious judgment could form, her body had already moved. The instant her mage's instinct sensed that Koichi's internal mana circuits had gone silent—before she could even shout, her hands were on the ladder. Ren was stabilizing the ladder's base from the ground. Calmly but surely directing the gathering residents' gazes away. Moving in a way that made it seem like nothing was wrong, yet his eyes already held the worst-case scenario in view. "Koichi, don't let go." Her voice was small. She was right there. Serika placed her hand on Koichi's arm and cast a water-type calming spell. A first-aid measure that gently drew mana from the atmosphere into the body to settle an overloaded mana circuit. There was no pain. Just the haze's outline gradually thinning—not completely clearing, but sensation returning to the ground. The skill remained silent. "It's okay, let's go down together. I'm right here with you." Koichi wasn't in a state to receive those words. He couldn't believe "it's okay" applied to him now, and he didn't have the composure to listen to encouragement honestly. In his hazy memories, only the tactile sensation of the stones he'd stacked this morning remained in his palms. Looking at his hands, nothing happened. That asymmetry pierced his chest in a way that had no words. But when Serika said only "let's go down." Koichi didn't resist. He didn't respond. He simply followed Serika's words and reached for the ladder. --- Once on the ground, Ren approached. They moved to the wall beside the traveling crane's sleeping quarters, away from residents' eyes, and Ren quietly organized the situation. There was no emotion. Just a clear statement of facts. "One watchtower incomplete. One-third of the wall remains unfinished." Koichi heard those words while looking up at the traveling crane's sleeping quarters' beam. The roof's angle of inclination came to mind. Even though confirming the beam's angle here and now meant nothing, his concentration had broken and his habitual thinking was trying to return to its usual place. While calculating, he didn't have to think too much. So now that his hands had stopped, only his head sought the form of calculation. Serika saw this and covered her mouth slightly. She couldn't laugh. Yet somehow couldn't laugh—that kind of gesture. Seeing Koichi looking up at the beam trying to calculate the inclination, in this moment it looked like "nowhere to escape," and Serika couldn't say anything. "There's one more report." Ren's voice changed. Slightly, but definitely. "During this morning's patrol, I heard rumors spreading among the residents. That the Building Master's power won't last long. That this city will eventually perish." Silence fell. "I traced the source. A merchant-like man who's been staying since the third night's name surfaced. The man who was counting pillars outside the bonfire circle. He's disappeared this morning." Serika's expression changed. That man—Koichi thought the same. The man Serika had said "maybe he wants reference for business" about. Koichi had answered "perhaps so" and returned to his notebook calculations. Regret seeped into Serika's expression—the regret of "I noticed then but let it pass." She bit her lip, dropping her gaze to the ground. Ren said this was the work of the帳幕院—an intelligence organization that ostensibly ran a trade mediation business while embedding operatives throughout various regions to conduct information manipulation and public opinion control, with rumors of their covert activities long circulating throughout the ash plains. There was no emotional fluctuation in his voice. But his eyes showed how long he'd been suspecting this information. Probably since yesterday, he'd been tracing that man's behavioral patterns in his mind. "Why spread this rumor now?" Serika murmured. "Akatsugu has reached a stage where intervention should be considered. The city is taking shape, people are gathering, the Building Master's power has been demonstrated. As a force disrupting the balance, they've begun work to weaken it." Koichi was looking at his notebook. The incomplete work items on the progress chart remained, unmarked with completion lines. --- At dusk, Koichi went alone to the sunlit plaza. Akatsugu's market—the trading facility Koichi had built first, with twelve roofed stalls arranged in the center of the ash plains—still had residents exchanging evening meal ingredients. In this place where the blessing effect dwelled, trust in transactions naturally heightened. Even now that Koichi c