Bayu spent almost the entire day around his hiding place. He didn't dare venture too far until the analysis device had recovered enough energy. The internal solar panel continued working beneath the sunlight filtering through the gaps in the trees, slowly charging the Temporal Displacement Unit. The process was painfully slow, but after several hours, the energy indicator that had previously remained in the teens finally began to rise steadily. Bayu used the time to observe his surroundings. From his elevated position, he could see part of the forest stretching around him. Several herds of herbivores moved between the trees, while the occasional screech of flying creatures echoed above the canopy. Every now and then, a massive roar rumbled in the distance, keeping Bayu firmly in place. He didn't want to repeat his previous mistake. As the sun began to sink toward the west, the device's indicator finally changed. ENERGY RESERVE: 100% Bayu stared at the number in relief. "Good." He lifted the device and checked all the systems that had previously been unavailable due to the energy limitations. The environmental scan was now operating at full capacity, while several locked functions had begun to unlock. But before Bayu could check them one by one, the device suddenly vibrated. ANOMALOUS TEMPORAL SIGNAL DETECTED Bayu frowned. The signal was coming from underground. He aimed the device toward the stone floor inside the Eden-0 facility. A blue line appeared on the map. DEPTH: 18.7 M Bayu stared at the scan result. "Eighteen meters?" He returned to the hidden chamber and examined the wall he had previously assumed was nothing more than part of the ancient structure. This time, he activated the high-resolution material scanner. The result made his eyes widen. HIDDEN ACCESS Bayu cleared away the layer of dirt covering one section of the wall. After several minutes, he uncovered a square-shaped panel. There was no handle. No button. Only a small symbol resembling the Eden-0 logo. Bayu pressed the analysis device against its surface. IDENTIFICATION CONFIRMED EDEN-0 PERSONNEL ACCESS Then a mechanical sound came from beneath the ground. KRRR... Bayu took a step backward. The wall slowly shifted. A hidden underground door opened. Cold air escaped through the gap. Bayu stood motionless for several seconds. The logical part of his mind told him not to go inside. But his curiosity was far stronger. He switched on the device's light and descended the stairs hidden behind the door. The staircase was still intact. That alone was enough to send a chill down Bayu's spine. If this structure had truly been here for millions of years, not a single part of it should still have been functional. Yet this facility did not seem to follow normal rules. The deeper he went, the more traces of advanced technology he discovered. Cables were embedded in the walls, along with control panels, emergency lights, and several tightly sealed rooms. There were no corpses. No humans. Only the remnants of a technological civilization that should never have existed. After descending for several minutes, Bayu finally reached a massive chamber. At the center of the room stood a circular structure. Several glass cylinders surrounded it, most of them shattered. Bayu aimed his analysis device at the structure. EDEN-0 CENTRAL BIOLOGICAL FACILITY He moved closer. Behind the main structure was a panel that was still glowing. Text appeared on the screen. PROJECT EDEN-0 PRIMARY OBJECTIVE: HUMAN ADAPTATION TO PRIMITIVE BIOSPHERE Bayu read the sentence twice. "Human adaptation?" He opened the next set of data. Most of the files were corrupted, but one category remained readable. BIOLOGICAL ADAPTATION SERUM Bayu held his breath. At the center of the room stood a small container protected by a thick layer of glass. Inside was a silvery-blue liquid. Unlike the Chrono-Core, the liquid did not emit light on its own. But when the room's lights illuminated its surface, tiny particles could be seen moving through the serum like a living mist. Bayu stepped closer. The analysis device immediately began scanning it. EDEN-0 ADAPTATION SERUM STATUS: STABLE TARGET: HUMAN BIOLOGICAL SYSTEM FUNCTION: ADAPTIVE RESPONSE ENHANCEMENT PHYSIOLOGICAL STRESS TOLERANCE: + MUSCLE RESPONSE: + THERMOREGULATION: + ENVIRONMENTAL ADAPTATION: + Bayu fell silent. So this was why the facility had been built. They hadn't merely wanted to observe life in the prehistoric world. They had been trying to make humans capable of surviving in it. Bayu stared at the serum container. Countless questions raced through his mind. How long could the serum remain stable? What were its side effects? Why had the project been abandoned? And most importantly... Why was the serum still here? But there was no time to search for answers. Bayu broke the mechanical lock on the storage container using a tool from the field kit. After several attempts, the lid finally opened. A single small vial lay inside. EDEN-0 ADAPTATION SERUM — SAMPLE 01 Bayu carefully picked it up. The moment the vial was removed from its slot, the entire room suddenly began to shake. GROOOOM! Bayu nearly fell. "What now?" The lights flickered. Ancient panels lit up red. WARNING CENTRAL CONTAINMENT FAILURE Bayu looked around. Cracks began spreading across the walls. Dust fell from the ceiling. "Don't tell me..." He immediately ran toward the exit. But after only a few steps, an explosion erupted behind him. BOOM! One of the glass cylinders shattered. Then the ceiling collapsed. Bayu threw himself forward just as a massive chunk of material slammed into the floor behind him. The shockwave hurled him against the wall. Pain shot from his back all the way to his head. He tried to get up. He couldn't. "Get up..." Bayu forced both hands against the ground, trying to push himself upright. "Get up!" The cracking sounds grew louder. The entire Eden-0 facility was beginning to collapse. Bayu ran up the stairs with the serum still clutched tightly in his hand. Sections of the staircase collapsed moments after he passed them. Dust filled the air, blurring his vision. Then a massive beam fell from above. Bayu barely had time to raise his arm. CRASH! His body was thrown out through the underground entrance. He rolled across the ground. Behind him, the entire facility collapsed. The earth rose like a wave. Trees shook violently. Rocks tumbled down the slope. Bayu tried to crawl away while coughing violently. "Seriously...?" Before he could even catch his breath, the ground beneath him began shaking again. Bayu immediately got up and ran. He didn't know whether the collapse would attract other predators, but he had no intention of finding out. He ran as far as he could until he finally spotted a gigantic tree whose roots had created a hollow space beneath it. Bayu immediately crawled inside. The massive roots were large enough to conceal his entire body from outside view. He lay on the ground and waited. Several minutes later, the rumbling from the collapsed facility gradually faded away. Bayu checked his body. His old wounds still hurt, and now his back felt as if it had been struck by a boulder. But there was something far more important in his hand. The serum vial. Bayu pulled it out. The silvery-blue liquid was still intact. He stared at the label. SAMPLE 01 Bayu remembered the scan results. The serum had been designed to enhance the human body's ability to adapt to a primitive environment. In theory, it might be his best chance of surviving. But theory didn't always mean safe. Bayu knew that injecting an experimental biological substance into his body without knowing its side effects was an incredibly stupid thing to do. He also knew that waiting too long might be just as stupid. Out there were predators capable of catching him with ease. Plants he had never seen before. Parasites and microorganisms that had never entered the database of modern humanity. And he didn't even have a truly safe place to live. Bayu stared at the serum. "If this was really made for humans..." He took a deep breath. "...I hope my body still counts as human." Bayu removed the vial's cap. His hand trembled slightly. He found an injection needle inside the field kit and attached the vial. For several seconds, he simply stared at the needle. Then he injected it into his arm. The blue liquid entered his body. Nothing happened. Bayu almost let out a sigh of relief. Then the pain came. His entire body immediately tensed. "Ugh—!" He grabbed the tree root so tightly that his fingernails nearly dug into the bark. Heat spread from the injection site through his entire arm, then moved toward his chest and back. Bayu's breathing became ragged. His heart began pounding rapidly. "Ah...!" He writhed beneath the roots. His muscles tightened uncontrollably, while his entire body felt as though it were burning from the inside. Every nerve seemed to receive thousands of signals at once. Bayu bit down on his own arm to keep himself from screaming too loudly. He had no idea what was happening. But he knew one thing. The serum was working. Several minutes later, the pain began to subside. Bayu's body collapsed onto the ground. Sweat soaked his entire body. He gasped for breath while staring at the sky through the gaps between the roots. For a while, he simply lay there. Then he noticed something different. Bayu moved his fingers. There was no pain. He clenched his fist. The muscles in his arm felt denser. He tried to sit up. His body felt much lighter. Bayu slowly stood. His balance felt different. More stable. His hearing also seemed sharper. He could hear tiny insects moving through the grass, even the sound of leaves rustling several meters away. Bayu picked up a nearby rock. It was fairly large. He gripped it and applied a little pressure. Crack. A small fracture appeared across its surface. Bayu immediately released the rock. "...What?" He stared at his own hand. The enhancement hadn't turned him into a monster. He was still human. But his body felt more efficient. His muscle response was faster. His breathing was more controlled. His vision felt sharper. And the exhaustion that had weighed so heavily on him was slowly disappearing. Bayu immediately activated the analysis device. BIOLOGICAL SELF-SCAN The scan took several seconds. Then the results appeared. SUBJECT: HUMAN ADAPTIVE MODIFICATION: STABLE MUSCLE EFFICIENCY: +8.4% REFLEX RESPONSE: +11.7% THERMOREGULATION: +9.2% OXYGEN UTILIZATION: +7.8% Bayu read the numbers with widened eyes. The increases weren't spectacular. But combined, those improvements could mean the difference between life and death in an environment like this. He opened the additional scan results. A new line appeared. SURVIVAL ADAPTATION PROFILE: HUNTER MODE Bayu froze. "Hunter Mode?" The device automatically provided an explanation. ENVIRONMENTAL PROFILE DETECTED. PRIMITIVE BIOSPHERE ADAPTATION PRIORITY: PREDATOR AVOIDANCE / RESOURCE ACQUISITION PHYSIOLOGICAL ADAPTATION: ACTIVE Bayu stared at the screen for a long moment. So the serum didn't simply enhance his body at random. It adapted his body to the environment. And the environment he was currently in... was a world filled with predators. Bayu slowly emerged from beneath the roots. For the first time since arriving in the prehistoric era, he didn't immediately feel like prey waiting to be eaten. He was still weak. Still hungry. Still without a proper weapon. And he still had no idea how to return to the future. But his body had changed. Only slightly. Yet it was enough to give him a chance. Bayu took the small knife from the field kit and tucked it into his waistband. Then he stared at the forest, now being swallowed by the fading light of dusk. "All right." He took a deep breath. "If this world really wants to kill me..." Bayu tightened his grip around the knife. "...then I have to learn how to become part of the food chain." Far away in the forest, a roar echoed through the trees. Bayu turned toward it. This time, he didn't run. He stood still and listened. The sound was far away. Bayu could even estimate the direction it had come from. His eyes narrowed. His body reacted faster than his thoughts. He was beginning to understand what had changed. The Eden-0 serum hadn't given him the strength to conquer the prehistoric world. It had given him something far more important. A chance to survive. And in a world like this, even the smallest chance could mean the difference between a human who lived... and a human who became food.

Chapter 4 — The Eden-0 Serum