They walked in silence for a while, their footsteps echoing through the empty tunnel. The walls felt closer now, like the shadows themselves were listening.
"We're close," Rei said, stopping near a sealed door covered in dust and rusted locks.
Kaito looked at it. "What's in there?"
Rei pressed her hand against the door. "The Signal Room. It used to control the Echo Line... but now it connects to the deeper parts of the Hidden."
She took out a small key from her pocket—old and silver. She unlocked the door, and it creaked open with a loud groan. A wave of cold air hit them as they stepped inside.
The room was filled with broken monitors, tangled wires, and glowing screens that shouldn't have had power. On the far wall, something was scribbled in red: "Don't Listen to the Voices."
Kaito swallowed. "What is this place?"
Rei didn't answer right away. She walked to one of the working monitors and turned a dial. Static filled the room—then a voice cut through.
"…he's here… watching…"
The voice was faint, cracked like old glass. It repeated, again and again.
"…he's here… watching…"
Kaito felt a chill go down his spine.
"It's a warning," Rei said quietly. "Someone—or something—is tracking us. It knows we're in the Hidden now."
Kaito stepped back. "How? We've been careful."
Rei turned to him. "The coin connects you to the Hidden. But it also connects the Hidden… to you."
Suddenly, one of the broken monitors flashed. A face appeared—blurry, twisted, but watching them. Its eyes locked onto Kaito's. And then it smiled.
The screen shattered.
"Time's up," Rei said. "We need to move."