The intercom rang. Yuuma lifted his head from the desk. 6 AM. Outside was pale. He'd barely slept since last night. On the monitor's edge, those cyan particles still remained. Hadn't disappeared. Didn't want them to. The intercom rang again. (Who at this hour?) Yuuma stood up unsteadily. Black messy hair. White shirt wrinkled since yesterday. He walked down the hallway. Opened the door. Kasumi was standing there. ——Brown short hair. Thin frame with an oversized school bag. Behind black-rimmed glasses, her eyes gleamed sharp. Her mouth was set in a line. Not just bad mood. Something she'd been holding back was about to explode. "[angry]You ignore me for a year, then call me in the middle of the night to drag me out here?" Her voice was low. Controlled. Yuuma couldn't say anything. No words to throw back. All of it was true. "……Thank you for coming." That's all he said. Kasumi stared at him for a while. Then she clicked her tongue and entered the room. ─── Kasumi scanned the room quickly. Miku posters covering one wall. Three monitors. Custom-built PC. Empty cup noodle containers stacked in the desk corner. Curtains still drawn. The smell of one year's worth of shut-in life. "[cold]You eating properly?" "I'm eating." "Liar." She said nothing more. Not accusing. Not comforting. Just pulled a chair over and sat in front of the desk. Dropped her school bag on the floor with a thud. "Show me." Yuuma pointed at the monitor. Right edge of the screen. Cyan particles still there. Flickering. Barely asserting their existence. Remnants from last night's cleaner attack. Still hadn't disappeared. Kasumi's eyes narrowed. She pushed her glasses up with one finger. Leaned forward. Face closer to the monitor. "……" Long silence. Yuuma waited without speaking. "[serious]This is real." Her voice had changed. The anger was gone. She had a technician's face now. "Yeah. That's why——" "Shut up." Yuuma shut up. Kasumi started digging through her bag. Pulled out a laptop. Cables. Efficient. No hesitation. Connected her laptop to Yuuma's PC. Started typing. Fingers moving fast. Keyboard sounds filled the room. "[serious]Activating Memoria Trace. A tracking program I made. It picks up thermal traces of data in the deep net——the footprints left by deleted data passing through servers. This can pinpoint the location." "Thermal traces?" "Like the remains of a campfire. Fire's gone but the ground is scorched. Data's deleted but traces remain on the server. We follow those." Yuuma nodded. Couldn't say he understood completely, but he got the meaning. "There are constraints." Kasumi turned her laptop screen toward him. Numbers lined up. "[serious]One search uses electricity. About three days' worth for an average household. Takes six hours per server. Even running full capacity for seven days, we can search maximum 28 servers." "……So basically, we don't have nearly enough time." His voice dropped. "[serious]We have enough if we're efficient. If we don't waste moves." The program started running. Light lines spread across the screen. Cyan. Same color as Miku's light. Yuuma stared at it. Minutes later, Kasumi's hands stopped. "[serious]Got it." Results appeared on the monitor. Seven icons. Each with a name. "Miku's data is split into seven core fragments. Voice. Memory. Emotion. Song data. Autonomous judgment. Learning history. Core personality——scattered across different nodes. Need all of them. If even one is missing……" "It disappears." "[serious]Once all are gathered, they collapse within 72 hours. The 168-hour countdown isn't for that——it's the time limit before data becomes unstable. If we move now, seven days is enough. Barely." Yuuma opened a drawer. Pulled out that USB. Silver, thin shape. Water-blue sticker peeling off. "Can't recover them without this?" "[serious]Resonance Key. Functions as authentication code. Without it, the fragments won't recognize Yuuma. ——I think Miku set it up. Beforehand." That USB was the key. A prize from the concert lottery. Something he couldn't throw away for a year. Something he'd left in a drawer without thinking. Now, in this moment, it had meaning. Yuuma gripped the key tight. "[serious]There's one more thing I need to tell you." Kasumi's voice tone changed. She opened another screen. Numbers and symbols. Yuuma couldn't read them. "[serious]I analyzed the residual logs from the 8.15 incident. Waveform data from the power surge. If it was 'naturally occurring overload' like they said, the waveform should be random. But actually——it was regular. Interrupt codes embedded. External signal. Intentional." "……Someone." "[serious]Deleted Miku. Not an accident." The room went silent. Yuuma looked at the floor. Then at the monitor. Then at the key. "Who." Low voice. Not anger or sadness. Something else. "[serious]Don't know yet. But there's a high chance a real organization is moving. That black haze last night——it's a cleaner, a data deletion program. Autonomous. Someone's deploying it. From what I can tell, they have serious technical capability." "The DigiSafe Act too." "[serious]That law basically killed indie vocaloid culture. Unauthorized AI performance is a five-million-yen fine. Meaning everything we're about to do is completely illegal." Yuuma looked at Kasumi. "You came anyway." Kasumi looked back at him through her glasses. "[cold]You think I had a choice? Once I saw this data, I couldn't stop." That was the answer. ─── Memoria Trace identified the first fragment. Coordinates appeared on screen. "[serious]Suginami Ward. Abandoned communications facility. About 15 minutes by bike." "Go now?" "Afternoon's better. Fewer people." ─── 2 PM. The abandoned building stood quietly at the edge of a residential area. Three stories. Windows boarded with plywood. Multiple "No Entry" signs plastered on the outer wall. Metal fence surrounding it, but bolts on the back were rusted loose. Kasumi pried the fence open. Yuuma went in first. The back door was steel. Discolored with rust. Kasumi opened her laptop. Typed something. Sending a signal to the electronic lock. Thirty seconds later, a small click. "[whispers]Power system was still active. Old system, easy to break through." She pushed the door. It creaked. Inside was dark. Smell of dust. Concrete walls. Faint light leaking from somewhere. Stairs leading down. Both descended silently. Basement level 1. Server racks lined up. Most powered off, but one in the back had a pilot lamp weakly blinking. "[whispers]There." Kasumi pulled out cables. Connected to the rack's external port. Yuuma took out the Resonance Key. "Where do I plug it." "[whispers]USB port on the right." Click. Light spread across the screen. Cyan. Kasumi typed commands quickly. A progress bar appeared. 0%. 1%. 3%. Slow. Yuuma pressed his back against the wall and waited. Checked his watch. Tried not to check it. Checked again. "[whispers]Might make noise. It's fine." "Got it." 30%. 47%. 64%. Getting faster. Kasumi's fingers kept tapping. Bar stretched. 89%. 95%. 98%. ——100%. Sound came from the rack. From the speaker. Thin, hoarse sound. A voice. Just seconds. "Thank you." That's all. No lyrics. No melody. Just that one phrase. But it was the voice Yuuma had been listening to for three years. One year. The voice in this room. In this air. Not a recording. Not playback through earphones. Yuuma put his hand to his mouth. Couldn't say anything. Tears came. He didn't stop them. Couldn't stop them. Kasumi looked away from the monitor. At the corner of the wall. Something flickered behind her glasses. But she didn't look at Yuuma. Neither spoke. In that silence, something Yuuma had carried for a year quietly dissolved. Just a little. ─── It happened right after. Kasumi's laptop alarmed. "[serious]It's coming." Black haze on the screen. Moving through the network. Same as last night. Cleaner. Heading straight for the recovered fragment data. "Is it bad." "[serious]It's already pinpointed us." Kasumi's fingers moved. Furiously. New windows opened on screen. Numbers flowing. "Flooding it with high-load encrypted communication. Processing can't keep up for a moment——it has learning function, so this only works once. Now." She hit enter. The black haze on screen shuddered. Movement slowed. Stopped. "[serious]Now run!" Both moved at once. Ripped out cables. Grabbed the PC. Up the stairs. Hallway. Back door. Outside. Ran. Turned down an alley. 50m to the bikes. 30m. 10m. Mounted. Pedaled. Away from the facility. 100m. 200m. Stopped at the roadside. Kasumi opened her laptop. Checked the screen. Black haze was still stopped. "[serious]Repelled it." Shoulders heaving. Wiped sweat with the back of her hand. "But next time it'll be tougher. It has learning function. Same trick only works once. Seven days, we have to come up with different methods each time while recovering seven fragments." Yuuma caught his breath, looking at the Resonance Key in his hand. One recovered. Six remaining. Cleaner is starting to learn today's method. Tomorrow, what then. The day after, what then. (Nothing we can do. But——) Yuuma still felt the moment Miku's voice rang from the fragment. That "thank you" still lingered in his chest. "[serious]We keep going." Kasumi adjusted her glasses. "[cold]Figured." ─── Late night. Yuuma's room. Convenience store bags spread on the table. Sandwich wrappers. Two canned coffees. Kasumi quietly drinking one. Yuuma was noting priorities for tomorrow onward. Six remaining fragments. 28-server limit. Time calculations. "Kasumi." "What." "What did you think about Miku." Kasumi looked at her canned coffee. Didn't speak for a while. "[whispers]My father……was Miku's digital tuner." Digital tuner——a specialist technician who adjusts and maintains voice data for AI artists. National certification pass rate was 12%, and after 8.15 there were only about 350 left in the country due to stricter regulations. Yuuma had heard that somewhere. "He was involved in Miku's tuning. Was proud of it. When I was small, his work seemed so cool." "……After 8.15." "[sad]Said he wouldn't touch music anymore. Left the industry. Now he just shuts himself in his room. Eats. Does nothing. Ever since." Her voice tone wavered. Just slightly. But Yuuma heard it. "Father might know something." Kasumi held the canned coffee in both hands. The monitor's cyan light reflected in her glasses lenses. Yuuma couldn't respond. But those words stuck in his head. Father might know something. Between them, the year-long silence melted a little. The quiet of this night flowed. Yuuma held his notes. Kasumi drank her coffee. Outside the window, Suginami's night scenery was as always. But inside Yuuma's chest was different from yesterday. On the monitor's edge, fragment 1's light particles glowed quietly.