The memory always started with the sand. Warm, fine-grained, smelling faintly of salt and pine trees, and the small, sturdy hand of Jun 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 pitch—the sound of someone who had already seen too much of the world, having lost his parents before he could even 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, nestled between the rugged mountains and the sparkling waters near Atami, Jun was an anomaly—raised alone, with only the occasional visit from his distant government-appointed guardian. And Yui was his constant, his anchor, and his entire world.
The first time they made the promise, they were six. The promise 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 don't ever leave this town. If you wait, I'll always come home."
The next time, 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, I'll get a job that lets me 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 June 15th. Jun's fifteenth birthday.
Yui had baked him a lopsided cake with too much cream and presented it in the quiet, sparsely furnished house that was technically his own. 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.
The next morning, the silence of Jun's house was no longer muffled; it was deafening.
Yui arrived before school, carrying a forgotten gift she'd hidden under her bed. She knocked. No answer. She opened the familiar door (they never locked it).
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. He hadn't run away. He had simply... vanished.
In a small seaside town where everyone knew everyone, a missing person case quickly became an immediate, terrifying crisis. The police flipped every stone on the mountain trails. Yui's father organized search parties along the jagged coastline. The hope 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, a fisherman found a single, mud-caked shoe washed up beneath the old lighthouse. It was Jun's. The one he wore every single day.
The silence that followed was worse than the sound of the ocean, more painful than the desperate cries. It was the sound of a world being permanently broken. Yui felt the sun that Jun carried within her fade away, replaced by a hollow, endless dusk.