At the entrance to Mizuho Village, Senkū raised his hand lightly to the villagers. It was one of the scattered settlements deep within the Kantou Great Forest. Daylight filtered through the trees, illuminating the simple wooden houses. Ten days since their reunion. The pace at which Senkū and Yomi moved through the village had already become second nature to them. "Oh, the medical expert teacher came again," "[serious]This time there's two of us. I came along too," The villager looked at Senkū, then at Yomi standing beside him. Yomi had her deep purple long hair loosely tied back, silently checking her pen and notebook. Small moles at the corners of her eyes, amber irises. Her expression was calm, but a hint of exhaustion seeped through. "Are you from some science kingdom?" "[serious]That's right," "No, I am independent——" "Both," Their voices overlapped, and both fell silent at the same moment. Yomi's eyes drifted away slightly. Senkū brushed up the red mesh in his bangs with a nonchalant expression and started walking deeper into the village. ——That was the moment. "[excited]Big brother!!!!!" From deeper in the village, a roar erupted as silver-white short hair came flying at explosive speed. Small burn scars on his face, golden eyes gleaming—no, exploding with light. He crashed directly into Senkū's body. Thud. Senkū staggered. Yomi took half a step back. "[surprised]Whoa—!?" "[excited]For real!? You're actually my big brother!! I've wanted to meet you so bad!!" The boy—Kazeru Varuju, seventeen years old—hung from Senkū's arm while rattling off words without pause for breath. "[excited]The village elder wrote down records of your science videos on stone tablets, and I read all of them! Then I made experimental equipment from scrap materials and taught myself how to dilute nital solution, and the other day I made glass for the first time! It was totally full of impurities though!!" Senkū's eyes changed. His emerald green irises gradually regained their light. "[surprised]……You made equipment from scrap and taught yourself to make glass?" "[excited]Yeah!! I failed like a hundred times!!" Senkū's lips curved into a smile. "[laughing]That's 100 billion percent interesting," He laughed—genuinely, from the heart. Yomi saw that smile. For a moment, she froze. It was the same as that morning when Senkū reacted to Kohaku's radio. Something tightened in her chest, and she immediately looked away. "[excited]And hey, the spot next to big brother is my place!!" Kazeru pressed himself against Senkū's side. Then he glanced at Yomi. "[surprised]A medical expert? I don't really get it, but science is the best, right big brother! Let's do experiments together!!" There wasn't a shred of malice in it. That made it cut deeper. Yomi couldn't even bring herself to be angry. She pressed her lips together and said nothing. --- The village chief's house stood at the center of the village. An elderly man with white hair ushered Senkū and the others inside as he spoke. "Actually……we found something strange in the forest depths," "[serious]Something strange?" "It's about the size of a palm, hard like stone, and when you touch it, the surface glimmers……it glows. After seeing that, a hunter who was nearby developed some cracks in his skin," Senkū's eyes ignited. Before the village chief finished speaking, puzzle pieces were already clicking into place in Senkū's mind. Palm-sized. Surface that glows. Stone-like symptoms after contact. Medusa. The petrification ray—a fragment of the mysterious device that turned all of humanity to stone 3,700 years ago. It exists here, in physical form, near this village. "[excited]Where is it? Take me there right now, I——" "[excited]I know where it is!! I'll show you, big brother!!" Kazeru jumped up. Senkū and Kazeru exchanged a look. The two of them headed straight for the door. Senkū turned back to Yomi at the threshold. "[serious]The village patients—I'm counting on you," That was all he said. A word of trust—at least, that's what it meant to him. To Yomi, it sounded like: stay here and wait. Senkū and Kazeru walked side by side, already launching into talk about experiments. Kazeru said something. Senkū answered. Their figures receded toward the forest. If he has that boy, he doesn't need me. A research partner can be replaced easily enough—— Yomi couldn't stop that thought from crossing her mind. "[cold]……Let's go," She spread out her diagnostic tools toward the village chief, speaking to no one in particular. --- As she made her rounds checking the village patients, the situation quickly took a turn for the worse. Nine patients with Ishiyami. That much was still within expectations. The problem lay beyond that. Five other patients had collapsed with high fevers. No skin cracks, no stiffened joints. Their bodies burned with heat, and they vomited even when given water. The symptoms were completely different from Ishiyami. The disease pattern didn't match any pathogen Yomi knew. Whether it was a mutated bacterium from the petrified world or something entirely different, she couldn't determine. Without that answer, Yomi constructed conservative treatment: isolation, cooling, and fluid replacement. "Teacher, with this many patients, one person can't handle it……" "[cold]It's fine," "Are you really sure?" "[cold]I said it's fine," Evening came, and Senkū and Kazeru still hadn't returned. As Yomi ground medicinal herbs in a stone mortar, a small child from the village approached. "Medical expert lady……" "What is it?" "Your face is scary. It's kind of scary," The child started crying softly. Yomi froze for a moment, then stopped grinding and crouched down to the child's eye level. She relaxed her cheeks slightly. "[gentle]Sorry. I'm not scary," The child sniffled and slowly smiled. Yomi stood up. Her face returned to its usual state. The way her hands moved toward the mortar carried the weight of exhaustion. --- Night fell. Senkū and Kazeru returned when lights began to appear throughout the village. "[excited]Listen, Yomi! The crystal structure on the surface of the Medusa fragment matches the petrification ray's generation product! This needs analysis, right now——" Senkū rattled off words while spreading out experimental equipment. That was when Yomi swayed. Exhaustion and hunger made her legs unsteady. She caught herself against the wall, barely avoiding a fall. "[serious]Hey," Senkū rushed over to grab her arm. "[angry]Don't touch me," She pulled her hand away. "Go chase whatever you want—Medusa, petrification rays, it doesn't matter," Her voice trembled. Not from anger. "I was never in your sight from the beginning," Tears welled in Yomi's eyes. Her amber irises wavered. Everything she'd kept locked away spilled out as raw truth, worn thin by exhaustion. She'd been beside him for 3,700 years. There were words she'd tried to tell him before the petrification, words she never got to say. And yet, she'd never been seen. That frustration, that sorrow——it came pouring out now, here. Senkū froze. No words came. He couldn't say "it's scientific reasoning" or "data collection efficiency." Yomi's voice was completely different from usual. Not anger. A wounded voice—he understood that now. "Yomi, I——" In that moment. A scream pierced the night from deeper in the village. A high-fever patient had convulsed and collapsed. The family's cries tore through the darkness. Yomi wiped her eyes with her sleeve. Without hearing the rest of Senkū's words, she turned on her heel and ran. Senkū followed. The house was chaos. A young man convulsed on the floor. His fever exceeded forty degrees. Yomi knelt and observed while assembling treatment options. Senkū pulled usable items from their supplies. Even with both of them, they couldn't identify the cause. "What kind of bacterium……" "[serious]Not enough data. Too few cases," By the time they'd stabilized the patient, both were exhausted. --- That was when Kazeru returned. "[excited]Um, big brother……when I looked at the Medusa fragment a bit closer, it glowed. And my right hand……it turned to stone a little bit. Hehe," Kazeru held out his right hand. From his fingertips to the second knuckle, it was gray with petrification. No one spoke. Only the sound of "hehe" remained in the night's silence. A crease formed between Senkū's brows. Yomi placed her hand on her forehead. "[surprised]……Hehe?" "[serious]Not funny," "But it was smaller than I thought, and for real! It's just a little bit——" Senkū said nothing more. He checked the remaining nital solution in his supplies. If the petrification came from the same substance as the petrification ray, Kazeru's stone-spread could advance. Local application would barely use up what they had. But that was the portion they'd planned to use for treating the high-fever patients. Treat Kazeru's petrification now. Or devote all effort to identifying the village patients' illness. Choosing one meant the other might become irreversible. Senkū looked up. He looked at Yomi. Yomi wasn't looking at Senkū anymore. She quietly returned her diagnostic tools to her bag. Either way, she came second——she could read that answer in his eyes, and she pulled her bag closer. No one spoke it aloud. The three of them faced three different directions as the night stood still.