Night had fallen, and the lights of Emerald City flickered in the darkness, resembling stars that had descended from the heavens. Leo and Luna stood before the ancient giant tree at the city's center. Its tangled roots intertwined with the city's architecture, as if forming the lifeline of Emerald City itself.
"This is the place," Leo murmured, recalling the Starshine Incantation the city lord had taught them before his death. He took a deep breath, gazed up at the tree's weathered trunk, and slowly recited the unfamiliar yet oddly familiar words.
As the incantation faded, the tree's roots trembled slightly, and the ground shimmered with golden light. A hidden fissure slowly opened, revealing a descending passage. Luna blinked her left eye, silver starlight flashing faintly in her pupil.
"There's… a highly complex mechanical structure down there," she said softly, a strange familiarity in her voice.
Leo nodded, and together, they stepped into the fissure, their figures swallowed by the darkness.
Inside the passage, gears and plant roots spiraled together, forming an eerie yet magnificent spectacle. Metal and life blended seamlessly—both rigid and organic, as though the result of deliberate engineering or a miracle of nature itself. Ahead, a vast hall unfolded, with a pulsating mechanical heart suspended in its center. With each rhythmic beat, it released a stream of warm golden energy, flowing through the pipes into the tree's roots.
Leo frowned, watching the glowing tendrils seep with golden liquid. He muttered, "So this is… the purification system of Emerald City."
Luna stepped forward, her hand gently touching the mechanical heart's surface. A pulse ran through her fingertips—familiar, instinctual. The heart's rhythm matched her own mechanical core, perfectly synchronized.
Suddenly, Luna's left eye flared, projecting a silvery-white beam into the air. A hazy image materialized—a shadowed figure standing before this very tree, holding its energy heart, embedding runes, and constructing the core of this purification sanctuary. The figure's face… was Leo's.
Leo's pupils contracted, his body freezing in place.
"That… is me?" His voice was hoarse, disbelief thick in his tone. His mind spun. The energy heart planted in the past was completely different from the mechanical heart before them now—had someone replaced it?
Before he could process further, the image shattered. The mechanical heart convulsed violently, its gears spinning out of control. The sudden reversal of energy triggered a catastrophic malfunction. The ground beneath them trembled, walls began to collapse, and a powerful surge of energy erupted outward.
"Run!" Leo grabbed Luna's hand just as a colossal shockwave engulfed them, hurling them into the unknown abyss.
Cold water surged over them as they were pulled into a relentless whirlpool, tumbling downward until they were finally thrown onto a soft riverbed. Dimly glowing mushrooms bathed the damp cavern in an eerie blue light.
Leo coughed up water, struggling to sit up. Scattered around them were countless transparent glass capsules, each containing blurred images, like fragments of dreams sealed away. He picked one up, and a vision surfaced inside—the image of a child being scolded by his mother, tears glistening in his eyes before the memory faded.
"These are… the memories erased from Emerald City's people?" Luna whispered, her fingers brushing over the capsules, feeling the emotions trapped within.
Footsteps echoed from the darkness. A hooded figure emerged, stepping forward with a slow, deliberate pace. As he lifted his hood, his half-crystallized face was revealed—a face identical to that of the city lord.
"Welcome to the Exiles' Sanctuary," he said in a deep voice.
The exiles encircled them, their bodies partially crystallized, their eyes filled with sorrow and pain. These were the ones who had been the first to undergo the purification experiment, only to be deemed failures and cast away, forced to survive in the underground ruins, clinging to the discarded memories.
"Who are you?" Leo asked cautiously.
The elder answered slowly, "We were the first subjects of Emerald City's purification process." A bitter gleam flickered in his gaze. "The so-called 'purification' was nothing more than a lie dressed as salvation. We were the initial test subjects, but the process wasn't perfect. The pain wasn't erased—it was merely sealed within our bodies. Over time, it crystallized, turning us into monsters. To prevent panic, they abandoned us here, never allowing us to return to the surface."
Leo remained silent, his chest tightening with unspoken fury. The peace of Emerald City had been built upon these people's suffering.
At that moment, a sudden tremor rumbled through the cavern ceiling. Something fell from above, crashing heavily onto the ground.
The masked thief!
The thief struggled to his feet, his gaze scanning the surroundings before locking onto Leo. His pupils shrank in shock, his voice laced with disbelief.
"It's you!?"
Leo's heartbeat pounded. He stared at the familiar eyes, fragments of forgotten memories stirring within him, yet nothing surfaced.
"You… know me?" Leo asked in a low voice.
The thief didn't answer. He took a wary step back, seemingly weighing his options. Luna, watching closely, subtly raised her fingers, ready to act at a moment's notice.
But then—the tremors intensified. Above them, the mechanical heart's energy spiraled out of control, reversing at an unstable rate. A massive explosion was imminent.
The thief's expression shifted dramatically, his voice hoarse with urgency. "This isn't right. The tree's heart has been stable for years—why is it reversing now?"
Before anyone could respond, a raging tide of golden energy roared through the underground river, engulfing everything in its path.
Darkness descended once more.