Joo Idam. His name was like that of a shark swimming through the dark, deep ocean of data beneath the gleaming surface of the MainNet. A man with no official occupation, no registered address. But to Jin Doyoon, he was the most reliable—and perhaps the only—key he had.

Doyoon sent a brief message through an encrypted communication channel he'd written down in the corner of an old coding notebook. [FROM: D.J / TO: J.D / MESSAGE: "Forgotten melody, need a player."] It was their secret contact code, born from a small incident they'd solved together in the past.

The reply came a day later, short and concise. [FROM: J.D / TO: D.J / MESSAGE: "Tomorrow midnight, Neon Dream Arcade booth 7. Got your coins ready?"]

The next night, in a corner of the old district where City Bay's brilliant lights couldn't reach, only the sign of 'Neon Dream Arcade' flickered eerily. The place seemed to have been closed for ages—the entrance was covered in dust, and only a desolate wind circulated inside. Doyoon stood before booth 7, in front of a classic game machine called 'Space Warrior.' When he inserted an old commemorative coin into the slot, the screen dimly lit up, displaying not [INSERT COIN] but a different message.

[WELCOME, LOST PLAYER. PRESS START.]

When Doyoon pressed the start button, the wall beside the game machine slid open silently, revealing a dark passage. At its end, only the faint glow of monitor light seeped through.

"Long time no see, Jin Doyoon. Still wearing that same boring expression."

The voice came from where a man sat surrounded by piles of cables and components, with energy drink cans stacked like mountains around him. His dyed silver hair stood out even in the darkness, and though dark circles shadowed his eyes, a mischievous smile played at his lips. It was Joo Idam.

"You haven't changed either, Joo Idam. When are you going to start living in some sunlight?" Doyoon said as he sat down across from him.

Idam shrugged and turned away from his monitor. "What if I develop a sunlight allergy? Will you take responsibility? So, what's this 'forgotten melody' about? If you're contacting me like this, it can't be ordinary."

Doyoon took a breath and told him about Chef Moon Gahyeon and Police Officer Oh Chanwoo. How both had completely vanished from everyone's memories and from all MainNet records. How only he remembered them in this bizarre phenomenon.

Throughout the story, Idam's expression remained cynical. "Hey, Jin Doyoon. Haven't you been sleeping lately? Or... maybe there's an error in that fancy neural chip of yours? Do you really think it makes sense for people to just disappear like that? This sounds like urban legend level stuff."

"I thought so too at first. But this isn't a mistake. These were people who definitely existed. My memories are too clear." Doyoon's voice was desperate.

Idam crossed his arms and stared at Doyoon for a moment. His eyes narrowed. "Hmm... seeing you go this far, maybe it's not complete nonsense after all. Fine, let's say someone intentionally deleted records like you claim. But why? Were these people planning world destruction or something?"

"I don't know. But this isn't simple record deletion. They're controlling people's memories too."

"Memory control..." Idam muttered, stroking his chin. "It's not technically impossible. If you reverse-engineer MainNet's 'Deep Dive' protocol, blocking or distorting specific memory patterns is theoretically possible. Of course, it would require enormous authority and resources. This is practically venturing into godlike territory."

He pulled out his device and began searching rapidly. His fingers danced through encrypted networks with dazzling speed, then suddenly stopped.

"Found something interesting." Idam's eyes sparkled. "In recent months, there's been an abnormal increase in log access related to 'Existence Value Assessment Algorithms' in MainNet's central management system. And there are traces of secretly modified personal information access permissions for specific conditions—people with weak social networks or low public data contribution scores."

Doyoon swallowed hard. "Could that... be related to the 'vanished ones'?"

"Can't say for certain yet. But the timing is remarkably coincidental." Idam turned his monitor screen toward Doyoon. It was filled with complex graphs and code. "Those people you mentioned—Moon Gahyeon and Oh Chanwoo—did they have anything in common?"

"Well... Chef Moon was about to become famous enough to be nominated for Asia's Top Chef Award, and Detective Oh was investigating corporate corruption. I can't really think of any common ground..."

"No, not surface-level stuff like that. I mean their 'digital footprints.' Things like MainNet dependency levels or neural chip data sharing settings."

Doyoon furrowed his brow. Come to think of it, Chef Moon had said "momentary experiences matter more than records" when discussing his culinary philosophy, and Detective Oh was known for carrying around an old-fashioned notebook and preferring on-foot investigations.

"Maybe... they were people who were uncooperative with MainNet systems, or beyond the scope of control."

A meaningful smile crossed Idam's lips again. "Bingo. That's highly likely. So, what now? Are you planning to prove your 'ghost friends' existed? Or are you going to uncover this massive conspiracy and serve up some justice?"

Doyoon looked straight into Idam's eyes. "At least... I need to understand why this is happening. And I can't just stand by and watch more people vanish so meaninglessly."

Idam stared at Doyoon silently for a moment, then chuckled and stood up. "Alright, Jin Doyoon. That frustratingly righteous attitude of yours—it's actually nice to see again after so long. Nothing to lose, right? I'll try tracking your 'disappearing people.' But I have conditions."

"Conditions?"

"Never lie to me. And... don't be too shocked by my methods." Idam winked. "But you know, this kind of perfect data erasure and memory control... it's quite familiar handiwork. Almost like... the way those 'Blankers' who operate in MainNet's shadows would work."

'Blankers?' It was the first time he'd heard that name. Doyoon's eyebrows twitched.

Idam was already starting to gather his equipment. "Well then, shall we begin? Our first objective is... finding the next 'scheduled for erasure' person. We need to figure out what pattern they're following."

In the darkness, the two men's eyes met. The first page of a massive mystery was about to be turned.