Kia swam gracefully along the border of Atlantis, her body carried by the oxygenated current that hummed softly through the water. This engineering marvel, designed to ensure the survival of the Atlanteans beneath the crushing depths, encircled the city like an invisible guardian. She stretched out her hand, gripping one of the handholds embedded along the dome's inner surface, and paused to catch her breath. Below her, the amphitheater loomed in shadow, its grand, arching seats eerily empty.

Her advisors would be expecting her there soon. Another day, another speech—a carefully prepared set of comforting words meant to ease the growing anxiety of the populace. The cracks in the dome, faint but unmistakable, had become a symbol of Atlantis's slow decay. Though the oxygen currents still flowed and the lights in the crystalline towers still shone, the city itself was dying.

But Kia could hardly bear the thought of standing before her people today. She had always preferred her sojourns beyond the safety of the dome, out in the vast unknown where she could explore, dream, and—however briefly—forget the burden of being Atlantis's last hope.

With a deep breath, she swung out of the current and slipped through a hidden breach in the barrier, a fissure she had discovered during one of her many secret escapades. The moment she crossed the threshold into the open ocean, she affixed a rebreather to her mouth, the device adapting the surrounding water's oxygen to breathable levels. It whirred faintly, sending soft vibrations through her jaw as it calibrated.

Her dark hair fanned out around her like ink in the water, and her necklace, a delicate pendant that swung freely on its chain, tangled itself in her locks. Kia brushed it free, her fingers instinctively closing around the smooth surface of the pendant.

"Pateh…" she whispered, the Atlantean word for "Father," though it was not her biological father to whom she referred. Kia flipped open the small locket, revealing a carefully preserved image of a human man—a traveler who had once wandered into their midst long ago. Byakuya Ishigami.

She gazed at the face in the locket, her heart heavy with both hope and despair. No matter how far she swam, no matter how thoroughly she scoured the endless ocean beyond the dome, she had found no trace of him. Byakuya was human, not of the long-lived Atlantean race. The likelihood that he had survived all these centuries was vanishingly small. And yet, he had left behind whispers of knowledge—hints that humanity beyond Atlantis might hold the answers to save her crumbling city.

Kia tightened her grip on the locket. "If not him," she murmured, "then perhaps his descendants…" She let her words drift away into the vast, silent waters. If Byakuya's bloodline persisted, they might hold the key to unlocking the secrets of the Medusa, the crystal that powered Atlantis. A secret she could no longer afford to leave buried.

Her gaze shifted downward, past the glittering spires of Atlantis to the jagged, hollowed-out caves beneath the city. A faint, flickering light emanated from the depths. Her breath hitched as she thought of the danger lurking below. Rachelle.

The witch had lived in the shadows of Atlantis for as long as anyone could remember, a recluse who had long been suspected of plotting to seize the Medusa crystal for her own twisted purposes. Kia knew the mercenaries Rachelle commanded were ruthless—and relentless. If they gained control of the Medusa, they would wield its power to reshape the world, perhaps even destroy it.

Kia's fingers brushed against another object hanging around her neck: a smooth, metallic Medusa device. Every member of the royal family possessed one, an artifact of alien origin that had once been the key to Atlantis's unparalleled power. It granted the ability to parasitize the alien technology—to bend it to their will and command it as an extension of their own magic.

But Kia's Medusa was useless to her. The knowledge of how to awaken and use its power had been lost when her mother, the last wielder of the Medusa's true might, had perished. Kia's heart ached with the memory of her mother's strong, confident voice as she commanded the device to shield Atlantis all those centuries ago. Now, the device lay dormant, its secrets as unreachable as the stars.

Unless…

The locket in Kia's hand grew heavier as a realization settled over her. Byakuya. The human traveler had spoken of understanding the Medusa's mysteries in ways no Atlantean ever had. Perhaps it was his uniquely human perspective, his insatiable curiosity. Whatever the reason, he had left her hints—maps, notes, ideas—hidden within the journal pages she had rescued from her childhood.

Kia clutched the locket and the Medusa tighter, her resolve hardening. If she could not unlock the Medusa's power, the crystal would fall into Rachelle's hands, and Atlantis would be doomed. She needed the knowledge Byakuya had carried—whether it was buried with him or passed down through his bloodline.

"I will find you," she whispered to the locket. "Whatever forbidden power I must use, whatever cost I must pay, I will find the answers you left behind."

A shadow passed over the dome above her as something enormous moved in the water. Her time was running out. The mercenaries were closing in. Kia turned away from Atlantis, her rebreather humming softly, and swam into the vast unknown.

Xxx

Far above the ocean's surface, Senku Ishigami adjusted his goggles, staring at the glimmering outline of Atlantis beneath the waves. Beside him, Taiju was still gawking.

"Senku…" Taiju said, his voice full of awe. "This signal came from here, right? But how is that possible? That city's been underwater for thousands of years!"

Senku smirked, his sharp mind already buzzing with theories. "Oh, it's possible, all right. And if my dad really left me that signal, then there's a reason we're here. A ten billion percent important reason."

Beneath the waves, Kia swam faster, unaware of the ship above or the stranger who bore the same name as the traveler she sought.