Modern-day Japan
The morning sun barely filtered through the thin curtains of the small apartment as Kosei hurriedly grabbed his bag. Behind him, the faint glow of the television flickered in the quiet room.
"Hey, Kosei, don't you think you should turn off the TV before leaving?" his mother's voice floated in from the next room, laced with tiredness.
"Sorry, Mom," he called back, quickly clicking the remote off.
The news was still echoing in his mind as he pulled on his jacket. The screen had shown a group of researchers uncovering a ruin—one estimated to be over a million years old. Among the many artifacts, an ancient tablet had caught the world's attention, inscribed with tales that read like myth.
The anchor had described it as a story about a forgotten era when humanity was blessed by gods, when people were immortal and death only came from murder. A paradise lost to time, where generations mingled freely and diseases were unheard of.
Kosei had scoffed quietly at the story. Fiction, nothing more.
"Damn it, Kosei! Why are you always late?" a familiar voice snapped him back to reality as his older brother Hayashi's footsteps thudded behind him.
"I'm coming!" Kosei groaned, stuffing his books into his bag as he raced down the stairs.
His younger sister, Kaguya, trailed behind them both, tugging at Kosei's sleeve. "You two are always so slow. Hurry up, or we'll be late again!"
They all knew the routine—Hayashi would wait for Kosei so they could enter school together, sharing the punishment of tardiness. But today, Kosei had other plans.
"Hey, Kaguya," he said later, glancing over his shoulder as they reached the school gates. "Go home by yourself today, alright? Tell Mom I'm studying at a friend's."
Her brows furrowed in protest. "You always make me lie for you. This time, I won't."
"Come on, just this once. Please?"
Her stubbornness softened at last. "Fine. Just this once."
The day slipped by in a blur—class discussions, laughter with friends, and the usual teasing. One of them, a boy with an easy grin, nudged Kosei.
"So, how old is your sister again?"
"Thirteen. Seventh grade."
"Not that far behind us then," another chimed in.
The group laughed and joked, hours slipping by unnoticed.
Then, his phone vibrated sharply in his pocket.
"Dad?" Kosei answered breathlessly. "Is everything okay?"
"Get to the hospital. Now. It's urgent," his father's voice was strained.
"What happened?" Panic crept into his chest.
"I'll explain when you get here. Hurry."
The call ended abruptly.
Heart pounding, Kosei sprinted toward the hospital, ignoring the growing dread in his stomach.
When he arrived, his mother's face crumpled with tears. His father's eyes were dark with worry.
"Where is she?" Kosei demanded.
His mother's slap was sharp across his cheek.
"Where were you? You were supposed to be with her!"
His sister—Kaguya—had been hit by a truck. The doctors fought to save her, but she lay in a coma.
Kosei staggered back, his world shattering around him. He stumbled out of the room and into the cold morning air, running without direction until he found himself at the nearby shrine.
Kneeling by the ancient stone steps, he cried out to the gods. "Why her? Why not me? She's always been kind, respectful… she loves me. And I—" His voice cracked. "I'm the one who lies. Why does this happen to her?"
A shadow shifted behind him, and a voice—rough, commanding—cut through the silence.
"You think gods care about your pain? You're a demon, not a believer."
Kosei whirled around to see a tall man standing by the gate. His pale skin and blond hair seemed almost otherworldly.
"Demon? Who are you?"
The man smiled, eyes gleaming. "Call me John. And I know what you're going through."
"Stay away! Don't come near me!" Kosei backed up, heart hammering.
John chuckled softly. "Calm down. I'm here to help."
Reluctantly, Kosei followed him through the shrine gates into a world unlike any he had ever seen.
The shrine expanded into a vast, shadowy realm, filled with twisted shapes and monstrous forms lurking in the darkness.
Kosei's breath caught as he saw it—a figure draining the life from a man lying motionless.
"Monsters," John explained. "They cause the illnesses that plague humans. Heart monsters, like the one you see, bring sudden death and pain."
Kosei's skin prickled with fear and disbelief.
John placed a hand on his shoulder. "I've been fighting them for centuries. And you? You have a pure heart. I've been waiting for someone like you."
"Me? You're crazy."
"Maybe. But trust me. This is only the beginning."
As the monstrous creature let out a final, agonizing roar, John's voice rose in a chant.
"By the Seven Gods, I banish you to eternal sleep!"
The creature dissolved into shadows.
John handed Kosei a card. "Come find me when you're ready."
Kosei clutched the card, his mind spinning.
"One last thing," John said with a grin. "I am John I Tzimiske—the Immortal Emperor."
Kosei frowned. "You stole that name from a Byzantine emperor."
John laughed. "Names are just stories. What matters is what you do with yours."