The ominous red emergency lights flickered menacingly as regular metallic footsteps approached through the silence—the sound of terror itself. What finally emerged from the darkness had a human form, but it was not a living being. Its body was made of cold alloy, with only a single red optical sensor glowing in the face area, and deadly energy weapons mounted on both arms. It was the guardian of the 'Akasha Field'—a 'Sentinel.'

"My God... how many of those things are there?" Ju Idam muttered in horror. The Sentinel fired an energy blast at Doyun and Ju Idam without hesitation. Doyun instinctively pushed Ju Idam aside and rolled to the side. Where they had been standing just moments before, black scorch marks and the smell of burning filled the air.

"Analyzing... That thing operates on independent AI! External network interference won't work on it!" Ju Idam shouted as he quickly scanned the Sentinel's data with his portable device. Cold sweat beaded on his forehead.

The Sentinel continued its relentless attack without giving them any respite. Doyun barely dodged the attacks using the surrounding server racks as cover while observing the Sentinel's movements. This wasn't just a simple destruction robot. Its movements were calculated, its attacks precise—like a skilled hunter.

"We need to find a weakness! Something like that must have a vulnerability!" Doyun shouted, picking up a metal pipe from the floor. It had no value as a weapon, but he needed something in his hands.

Then, a powerful 'echo' penetrated Doyun's mind. It wasn't from the Sentinel. It was from the past—someone who had faced the Sentinel in this place—their fear and despair, and... for just a brief moment, a vision of the Sentinel's specific area sparking from overload.

'Left shoulder joint... overload... specific frequency shock...'

"Ju Idam! That thing's left shoulder! And do you happen to have... something like a high-frequency generator?" Doyun called out urgently.

"High frequency? I do have one, but it's an old data erasing device, so it's not very powerful..." Ju Idam looked puzzled but pulled out a small device from his bag.

"That'll work! While I distract it, get as close as possible to its left shoulder joint and activate it!"

The plan was reckless, but there was no other choice. Doyun charged at the Sentinel, swinging the pipe. The Sentinel's red sensor locked onto Doyun. Seizing the opportunity, Ju Idam moved like a cat, nimbly circling behind the server racks and slipping into the Sentinel's blind spot.

"Now!"

At Doyun's shout, Ju Idam pressed the high-frequency generator against the Sentinel's left shoulder joint area and activated it at maximum output. With a sharp, piercing noise—kiiiiiek—violent sparks erupted from the Sentinel's left shoulder! The Sentinel's movements seemed momentarily paralyzed as it staggered.

"It worked!"

But their joy was short-lived. The Sentinel quickly regained its balance and counterattacked even more fiercely. Its left arm was paralyzed, but the energy weapon on its right arm remained threatening.

"This won't end like this! We need to find the way to the 'Core Repository'!" Doyun recalled the rough structural diagram of the 'Akasha Field' from Noh Minsu's notebook. Beyond the sealed shutter, there must be another passage.

Even amid the battle, Doyun's eyes thoroughly scanned the surroundings. Finally, he spotted an old ventilation duct cover hidden behind a massive cooling unit. It was small, but seemed just large enough for two people to squeeze through.

"Ju Idam, over there!"

The two launched another coordinated attack. While Doyun squeezed out his last bit of strength to draw the Sentinel's attention, Ju Idam began tearing off the ventilation cover. The Sentinel's energy blast grazed past Ju Idam's back, drilling a hole in the wall.

"Damn, almost got it!"

Finally, the cover fell away, revealing a dark opening. Doyun pushed Ju Idam in first, then barely managed to slide himself into the ventilation duct. Behind them, they could feel the heat of the energy the Sentinel was emitting.

How long did they crawl through the narrow, dark ventilation duct? Finally, they dropped down into another space. It was a much older, seemingly abandoned area filled with dust and musty odors.

"Are we alive...?" Ju Idam gasped for breath. His clothes were torn and his entire body was covered in sweat and dust. Doyun was equally battered. Noh Minsu's notebook had been partially torn during the battle, but the crucial parts related to the 'Core Repository' barely remained intact.

Then, something caught against Doyun's foot. When he shone his flashlight on it, it was a skull. A human skull. And around it, countless skulls lay buried in the dust.

"What is this place...?"

Before their eyes appeared a steel door much more massive and imposing than any previous security device. The door bore no markings, but the overwhelming 'echo' flowing from within seemed to suffocate Doyun. The sound of thousands, tens of thousands, or perhaps far more beings' memories tangled together in anguished cries.

The 'realm of sleeping gods' that Noh Minsu had warned about. This was the entrance to the 'Core Repository.'

The door seemed to pulse very faintly, like a living giant heart.