The pencil rolled from Seiji's fingers and clattered against the desk.
He stared at his own hand for a moment, watching the way it shook faintly, the tendons straining under pale skin.
It wasn't fear at least, that's what he told himself. It was just exhaustion. That was all.
The page in front of him was half-filled with the loose sketch of a character he'd been doodling for weeks now, some caped hero standing defiantly with a blade too large to be practical. The kind of character he'd always admired, the kind of hero he sometimes imagined himself becoming.
But tonight, the character's smile seemed hollow, mocking.
Seiji leaned back, rubbing his temple.
"Something is going on." he muttered. The words sounded heavy in the still air.
His eyes flicked toward the folded paper at the corner of the desk.
The one he had started writing earlier.
The one he had avoided finishing.
It wasn't supposed to be like this. Letters were for happy things for confessions, for thank-yous, for dreams you didn't dare say out loud.
Not for… whatever this was.
He stood up and crossed the room, throwing himself on his bed and staring at the ceiling. The faint glow of the desk lamp painted soft shadows across the walls, but even those seemed too sharp tonight.
A knock at the door broke the silence.
"Seiji?"
His mother's voice was gentle, but there was that note of concern again.
"Don't stay up too late, okay?"
"I won't." he said automatically.
He heard his father's voice from the living room, warm and casual:
"We're turning in soon. Big day tomorrow!"
And then his mother again, brighter this time:
"Tomorrow is your birthday,Seiji! Remember that!"
He forced a small laugh. "Yeah… I know."
Their footsteps faded, and the quiet returned.
But it wasn't the same quiet as before.
The words stayed with him.
Tomorrow is your birthday.
He swallowed, staring at the darkened ceiling.
This might be the last time I hear them.
The thought was cold, bitter. But it refused to leave.
He sat up, restless.
The folded paper on the desk caught his eye again.
Seiji crossed the room and sat down. His hands hovered over it, fingers curling like he was about to touch something dangerous.
He didn't pick it up.
Not yet.
Instead, he grabbed a fresh page and a pen, setting the tip against the paper.
His reflection stared back at him from the dark window beside the desk, pale and serious.
Tomorrow.
Tomorrow it would happen.
Whether it was aliens, demons, or something worse, he could feel it in his bones.
Every instinct screamed at him that this was it. The day his life split in two.
He didn't write a single word yet, but the pen stayed in his hand like a weapon.
The air in the room felt heavier now, pressing in on him.
Outside, the wind shifted. The curtains swayed though the window was shut tight.
Seiji gritted his teeth and pushed himself to keep breathing, to stay calm.
Just one more night.
He dragged the pen across the page, stopping halfway through the first line.
His hand froze.
He didn't look down. He didn't need to.
He knew what it meant.
His chest tightened as he sat there, unmoving, the sound of his parents' voices still echoing faintly in his ears.
The house felt impossibly still.
Even the ticking clock on the wall seemed to have stopped.
At that moment, he thought he heard it again. faint, distant, but undeniable.
Soon.
His grip on the pen nearly snapped it in two.
He pushed the paper away.
If this was going to happen, he wouldn't be caught off guard.
He stood and faced the window, the night outside pale and watchful.
Tomorrow.
One way or another, tomorrow everything would change.
Seiji sat at his desk, motionless, eyes fixed on the paper before him. The glow from his lamp was pale and weak now, like even the bulb had grown tired. Outside the window, the world was still not quiet, but waiting.
He hadn't slept. Not even for a moment.
The house around him had shifted from evening warmth to midnight chill. Hours bled together until he stopped checking the clock. All he could hear was the faint scratching of his pen, the restless beating of his heart, and his own shallow breaths.
He was so close to finishing the letter. So close to telling them everything he couldn't say out loud. The words swam in his head, heavy and urgent, but he refused to look at the page.
He didn't know when it would happen.
He just knew it would.
The sun had begun to rise, pale orange creeping along the horizon, casting a faint line of light through the blinds. Morning. His pen trembled. His other hand gripped the edge of the desk so tightly his knuckles whitened.
I have to finish this before it happens.
The air shifted.
A low hum rippled through the room, almost too soft to hear at first. His hair rose at the back of his neck. He froze, the pen still in his hand.
Then the floor under him shuddered not like an earthquake, but like something massive and unseen had stepped too close.
He shoved back from the desk, chair screeching on the floor.
"Stop." he whispered. Then louder, "STOP!"
He planted both hands on the desk to steady himself, but the hum grew deeper, vibrating through his palms.
And then, like a voice slipping through the cracks of his own mind, it came:
"When the world needs you, will you answer?"
His heart lurched. His throat went dry.
"Yes!" Seiji shouted hoarsely. "I will! I always will no matter what it is! so let me go!"
Silence.
...
The air thickened, pressing down on him like a weight.
...
Then another voice the same voice, but deeper now, colder:
"If hatred swallows you whole… will you still rise?"
His grip faltered.
"I… I don't know." he whispered.
The circle on the floor a circle that hadn't been there a moment ago pulsed faintly, light seeping from nothingness like ink spreading through water. It grew brighter with each pulse, filling the room with a dim, otherworldly glow.
Seiji staggered back, but his heels caught the edge of the rug. He fell against the desk, gasping.
His parents' footsteps thundered down the hall.
"Seiji?!" his mother's voice, sharp with panic. "What's going on?!"
The door rattled, handle turning.
He was already dissolving.
First his feet gone from the ankles down, replaced with light. His hands flickered, the pen clattering to the floor.
"Mom! Dad!!" he shouted, voice cracking. "I'll come back! I promise! This is something you'll need to choose patience! Promise me you'll read this letter I wrote!"
The door slammed open. His father lunged into the room first, hair disheveled, eyes wide.
"SEIJI!!"
His mother followed, pale and shaking, reaching out.
But Seiji's torso was already breaking apart into drifting motes of light.
"SEIJI!" they screamed together, a sound that tore through the house.
He saw their faces horrified, disbelieving framed by the doorway. He reached for them, fingers already fading.
"I'll come back…" he said again, but the words were swallowed by the rising hum.
The glow swallowed his hands. His arms. His face.
The last thing he felt was his father's hand slicing through empty air where his arm should've been.
The last thing he saw was his mother's tears catching the morning light.
And just like that… I was gone from their world.
My world.
....
Haruto stood frozen in the doorway, breath shallow, one hand still outstretched where he'd tried to grab his son. Ayane clutched the frame behind him, her knuckles white, her lips trembling but silent. For a long, terrible moment, neither of them moved.
Then Haruto took a step forward. His knees felt weak, each step heavier than the last. He staggered to the desk, where the lamp flickered once, then steadied.
There, on the wood, lay the letter. The paper was smudged at the edges, Seiji's handwriting sprawling across it in dark, deliberate strokes. Haruto's hand hovered above it, shaking, before he finally picked it up. The paper felt warm, as if it still held his son's presence.
Ayane's eyes followed him. She wanted to say something. anything. but the words wouldn't come. Her chest rose and fell in small, sharp breaths.
Haruto swallowed hard and began to read aloud. His voice cracked on the first line:
"Something unusual is happening… this isn't mere hallucination, nor fleeting dreams.
This is reality. Tangible. Unforgiving. I'll have to compose a detailed paper, a written testament, to ensure my mom and dad understand that I will return."
...
His voice broke. He pressed his lips together, tears slipping down his cheeks.
"I've absorbed countless mangas, animes, folktales, even the most childish books, enough to recognize and piece together what I'm hearing, seeing, and feeling right now, and that thing I've fully recognized is without a doubt… a summoning ritual for a 'isekai hero.'
I've expected many things to happen but not an actual summoning ritual…"
...
Haruto lowered the page, staring at the words as if they might change if he blinked hard enough. Ayane stepped closer, her hands trembling at her sides.
Seiji's handwriting swam before Haruto's eyes. He forced himself to keep reading, his voice softer now, raw with grief:
"So… I'll go straight to the point… Dad. Mom."
...
He stopped for a heartbeat, the paper shaking in his grip.
Ayane finally whispered, "He… he knew…?" but her voice faded again.
Haruto's tears dripped onto the edge of the paper as he continued.
"To my beloved parents.
If you are reading this… it means I am already gone, transported elsewhere. But worry not, Dad, Mom… I will come back. So please, wait for me. Remember my words into your hearts…
I promise you this: do not despair over my absence. Do not let grief consume you. Instead, be patient, steadfast, and unshaken.
Because no matter what happens… I am coming back."
Haruto's hands tightened on the paper. He hadn't given Seiji his birthday present yet. He'd hidden it in his study, planning to surprise him tonight. A small, practical gift. Now it sat useless in its box.
Ayane stared at the letter, tears sliding silently down her cheeks. Her son's words burned into her heart, each stroke of ink a wound and a promise.
Haruto's voice wavered but he pressed on.
"At first, I perceived only strange hallucinations, relentless visions, and dreadful nightmares, which I chose to keep secret rather than burden you with them. For that, I am deeply sorry.
As your eyes trace these words, I am most likely already in a new world, perhaps an alternate dimension or an entirely different plane of existence.
Those so-called hallucinations and nightmares were not figments of my mind they were warnings, truths in disguise. Not illusions. Not falsehoods."
The room was silent except for Haruto's quiet sobs. Ayane reached out, her fingers brushing his arm but stopping short, as if even touch felt too fragile right now.
He lowered the letter, staring at the last lines. The ink was darker there, as if Seiji had pressed harder with his pen.
"—
Yours Truly,
Your Son,
Seiji Daiki"
For a long moment, there was nothing. Just the two of them, standing in their son's room as the morning sun spilled across the tatami, golden and indifferent.
Haruto stared at the signature until it blurred. "He… he left us." he whispered, voice hoarse. "Our son… he's gone…"
Ayane shook her head slowly. Her tears fell but her expression was strangely still, as if she was clinging to something deep inside. She stepped closer, laying her palm over Haruto's hand.
"He promised." she said softly. Her voice trembled, but there was an edge of steadiness in it. "He promised he would come back."
Haruto blinked at her, his mouth working soundlessly.
She squeezed his hand. "If we despair… if we break… we'll be breaking that promise ourselves. He asked us to wait."
Haruto's breath caught. He looked at her, at the woman who had raised Seiji beside him, at the tears shining in her eyes, and something shifted in his chest.
The ache didn't go away. But beneath it, a fragile thread of resolve began to form.
They stood there in silence, minutes stretching like hours. The house felt emptier than it ever had, and yet Seiji's presence clung to it still the smell of his shampoo on his pillow, the pen rolling to a stop on the desk, the faint heat where his hands had been moments ago.
Haruto folded the letter carefully, pressing it to his chest. "We'll wait." he murmured."We'll wait for you, Seiji. For No matter how long.."
Ayane wiped her eyes with the back of her sleeve. "Patience," she whispered. "Perseverance. Faith."
"Never despair."Haruto added quietly.
Their voices mingled in the small room, a fragile vow.
Outside, the sun had risen fully, casting long shadows across the street. Neighbors stirred, unaware of what had just happened inside the Daiki household. Birds sang, oblivious.
Haruto and Ayane stood in their son's room, alone yet not alone.
They didn't know where he had gone. They didn't know what he was facing.
But they knew one thing:
Seiji had promised them he would come back.
And they would hold that promise, as tightly as they had once held his hands.