The memory always started with the sand.
Warm, fine-grained, smelling faintly of salt and pine trees, and the small, sturdy hand of Jun Kuroda grasped tightly in hers.
"Don't let go, Yui-chan. You'll get washed away."
Even at three years old, Jun's voice had that calm, almost weary tone—the sound of someone who had already seen too much of the world.
He had lost his parents before he could form a proper memory of them.
But when he looked at her, those deep brown eyes would flicker with a light only she could ignite. A light that felt like the summer sun reflecting off the sea.
In this small, sleepy coastal town near Atami, Jun was an anomaly.
After his parents died, he spent his early years living in a local Children's Home, a quiet, structured facility for kids who couldn't be with their families.
It wasn't until he was eleven that a distant, government-appointed guardian finally secured permission for him to move back into his family's old, sea-battered house.
He still received only occasional, formal visits.
But Yui was his constant, his anchor, and his entire world.
The first time they made the promise, they were six.
It was always whispered, always on the same stretch of beach where they first met.
"When we grow up, Jun, we're going to live right here in your parents' old house. You'll be the husband, and I'll make you food every day!"
Jun, skinny and serious even in his kindergarten uniform, had simply nodded.
"If you promise not to cry, Yui. And if you are there for me, I'll always come home."
One quiet afternoon, they were twelve, perched precariously on the railing of the coastal overlook, watching the fishing boats come in.
"You know, Yui, when we get married, we'll get a house that lets us watch the sea from the window. Just like we're doing now. We'll be right here."
His words weren't filled with the dramatic intensity of a boy's first crush, but the quiet certainty of destiny.
It wasn't if they got married; it was simply when.
Their love didn't feel like a story from a manga; it felt like the quiet, inevitable turning of the seasons. It was simply the foundation of their small world.
The last time Yui heard that calm, earnest voice was on Jun's fifteenth birthday.
Yui had baked him a lopsided cake with too much cream and presented it in the quiet, sparsely furnished house.
She'd always found the house too silent, too large for one boy, but today it was filled with the sweet, synthetic scent of candles and the muffled laughter of her parents standing in the doorway.
"Make a wish, Jun."
He had looked at the small, flickering flame, then across the table at Yui, a faint, nostalgic smile gracing his lips.
His wish had always been the same: a quiet life, together.
"Happy birthday, Jun," Yui whispered, her heart aching with the familiar, intense joy of being completely, utterly loved.
Just like every other weekday, Yui arrived at seven-thirty sharp.
The ritual was a silent promise: she'd be waiting on his stone porch, and he'd open the door, school bag already slung over his shoulder, a sleepy, low greeting on his lips.
They'd walk the winding path to the main road together, the short, shared silence of their journey a comfortable habit.
They hadn't missed a morning walk in nine years.
But today, the door remained shut.
Yui stood on the cool, damp concrete, her school shoes tapping an impatient rhythm as the seconds stretched.
A strange prickle of unease started on her neck. Jun was the most punctual person she knew.
She knocked. A light, hesitant tap first. Then, louder.
No answer.
She tried the doorknob, finding it locked.
Immediately, Yui's hand went to the chain around her neck, pulling the spare, copper-colored key—the one he'd given her—from beneath her uniform shirt.
It was her constant, free access to his life, confirming her special status.
She fitted the key into the lock and twisted.
The air inside was cold.
His school bag was slumped against the wall, ready for the day. His favorite worn-out hoodie was draped over the back of his desk chair. His old, half-finished manga sat open on the table.
Nothing was missing.
In the pit of her stomach, Yui felt a cold, hard stone of conviction settle.
Ignoring the rational voice that suggested waiting, she fumbled for her phone. Her instinct screamed, and she reacted immediately, calling the police first, her voice a tight wire of forced calm as she reported a missing person.
Next, she called her parents, her short, sharp account leaving no room for argument: they needed to come right now.
She remained on the cool, damp concrete of the porch, clutching the spare key, her eyes fixed on the house door as if sheer willpower could force Jun to open it.
She waited there, vibrating with contained panic, until the distant, familiar siren signaled the police car's arrival.
The police arrived, a young officer taking down the details in a nervous, quiet voice.
He asked the careful, standard questions, the kind designed to check off boxes.
"Is it possible, Yui-chan, that a boy his age, without—without immediate family support—might have felt the need to run away? To start fresh?"
Yui didn't hesitate. The cold stone in her stomach hardened into bedrock.
She met the officer's eye with a fierce, absolute certainty that made him drop his pen.
"That's impossible," she stated, her voice sharp and clear, devoid of tears or doubt. "He never breaks a promise. Never. We were going to live in that house and watch the sea forever. He wouldn't just leave that."
She knew him like she knew the tide.
Jun Kuroda was many things—weary, quiet, prematurely serious—but he was not a liar, and he was not a breaker of promises.
In this small seaside town where everyone knew everyone, a missing person case quickly became an immediate, terrifying crisis.
The entire coastline, which had always felt like a comforting embrace, now felt like a vast, predatory mouth.
The police flipped every stone on the mountain trails, coordinating search dogs through the damp, pine-scented paths.
Yui's father, a large man who rarely showed emotion, organized search parties along the jagged coastline, piloting his fishing boat out into the chill currents, shouting Jun's name until his throat was raw.
The hope, brittle as dried seaweed, lasted exactly fourteen days.
Then, on a Tuesday morning, when the tide was at its lowest and the sky was the color of faded slate, old Mr. Sato, the fisherman who lived closest to the lighthouse, found it.
Tucked beneath the barnacle-crusted foundation of the old lighthouse, a single, mud-caked shoe had washed up.
It was Jun's.
The one he wore every single day.
The silence that followed was worse than the sound of the violent, endless ocean, more painful than the desperate, hollow cries that had already been spent.
It was the sound of a world being permanently broken.
The quiet certainty of destiny had been brutally, suddenly revoked.
Yui felt the sun that Jun carried within her—the light that felt like the sea reflecting off the water, her constant, her anchor—fade away, replaced by a hollow, endless dusk.