"The memory... tomb." Noh Min-su's final words still echoed vividly in their ears. Inside Joo Yi-dam's hideout, only heavy silence lingered. The possibility that 'erasure' might not be a simple phenomenon, but an intentional 'murder,' left both men in deep shock.

"Damn it, this is getting bigger and bigger." Joo Yi-dam cursed under his breath as he roughly ran his hand through his hair. "Former director of the MainNet Memory Ethics Committee... If they're willing to 'eliminate' someone of that caliber, whoever's behind this must be beyond our imagination."

Jin Do-yoon's eyes had turned colder than ever. Noh Min-su's desperate voice awakened another kind of anger that had been sleeping within him. Being forgotten—it could be a punishment worse than death itself. This long-held belief of his was crystallizing into certainty.

"We need to learn more about Noh Min-su," Do-yoon spoke. "He might have left some clues about this 'memory tomb.'"

Joo Yi-dam immediately got to work. His fingers moved like a storm across the keyboard, penetrating layer after layer of MainNet's ironclad security network. Personnel records, past research papers, classified project participation lists—like walking a tightrope, Yi-dam exploited vulnerabilities in MainNet's surveillance system to extract information.

"Found it." After a moment, Yi-dam's voice broke through. "Noh Min-su was the project director for the 'Memory Information Permanent Preservation and Disposal Criteria Restructuring Project.' And... while officially discontinued, there are records showing he secretly conducted unauthorized research under the name 'Akasha Field.'"

"Akasha Field?"

"Right. It's an ancient mystical term meaning 'the cosmic library where all memories are recorded.' It's likely either the official name for what Noh Min-su called the 'memory tomb,' or a core project related to it." Yi-dam brought up a complex data structure diagram on his monitor. "The problem is that access to this 'Akasha Field' is encrypted at MainNet's highest security level. Breaking through is nearly impossible."

Do-yoon recalled Noh Min-su's voice once more. 'Because I learned too much...' What exactly had he discovered? And what was happening in this 'memory tomb'?

Just then, a sharp warning alarm sounded from Yi-dam's system. [WARNING: Unauthorized access attempt detected. Tracking system activated.]

"Here we go again!" Yi-dam frantically reinforced his firewalls. "Did they catch our trail, or did they detect our access to Min-su's files?"

Do-yoon glanced out the window. Though the darkness of dawn still hung thick, he couldn't shake the chilling unease crawling up his spine—as if invisible eyes were watching them.

"Yi-dam, was there anything else on the data chip Min-su left? Even encrypted files?"

"Most of it's locked with military-grade algorithms. It would take years even with a supercomputer to decode." Yi-dam clicked his tongue. "But... there was one more thing. A tiny text file with the bizarre title 'Guide for Those Who Cross the River Lethe.'"

The River Lethe. The river of oblivion.

When they opened the file, it contained only incomprehensible sequences of numbers and symbols, along with strange patterns resembling ancient hieroglyphs—like some kind of cipher.

"This is..." Do-yoon studied the patterns carefully. He had a feeling he'd seen them somewhere before. His mental memory storage spun rapidly. Then suddenly, an image surfaced: Ha-yoon, his former lover who had worked with him on memory restoration projects. She had been fascinated by ancient symbolic systems and often sketched patterns like these.

"Ha-yoon... she researched these symbols."

With trembling hands, Do-yoon opened his personal device and searched through old research materials he'd exchanged with Ha-yoon. Finally, he found it: a file titled "Forgotten Languages and Their Symbolic Meanings" that Ha-yoon had compiled. Inside was a symbol that matched exactly with the patterns in Min-su's text file. And beside it...

'Symbol representing the entrance to an ancient underground city. Responds to specific frequencies.'

"Frequencies...?"

Do-yoon and Yi-dam looked at each other. The thought struck them simultaneously that the numbers and symbols Min-su had left might be codes representing specific frequencies.

Yi-dam immediately ran a program to convert the numbers into audio frequencies. When the converted frequency played through the speakers, an extremely low, eerie sound—barely audible to human ears—emanated.

"What do we use this frequency for?" Just as Yi-dam wondered aloud, a specific point on the underground structural map of City Bay, displayed in the corner of his monitor, began flashing red. It was a map he'd pulled up while trying to estimate the server location of 'Akasha Field.'

"This can't be..." Yi-dam's eyes widened. "This frequency is... resonating with ground resonance sensors in a specific area! Like... like a key opening a locked door!"

The flashing red point marked the outskirts of City Bay, in an area of underground bunkers that had been sealed off long ago. The 'memory tomb' was an actual physical location.

"We have to go," Do-yoon said without hesitation.

Yi-dam nodded as well. Having grasped the doorknob to truth, there was no turning back. Just as the two men were gathering their equipment to leave the hideout—

CRASH!

The hideout's rusty iron door crumpled inward with tremendous noise. Through the dust, armed figures in black combat gear and face-covering helmets burst in, weapons drawn. Strange flame-shaped insignias were emblazoned on their arms.

"Don't move! You're under arrest for violating MainNet Security Laws!"

One of the intruders shouted in a low voice. In his hand was what appeared to be a weapon for dispersing nerve gas. Do-yoon and Yi-dam were instantly cornered.