The car door shut with a heavy click that sounded louder than it should have. Maybe it was just me. Maybe it was because my ears were still ringing from all the noise at the party—clinking glasses, chatter of grown-ups, the crunch of sweets between my teeth.
Now everything was quiet. Too quiet.
I slumped into the leather seat, my stomach full, my hands sticky from sugar. I licked a bit of cream from my finger before wiping it on the inside of my hoodie sleeve. The chauffeur started the engine, and the whole car hummed as we pulled away from the glittering lights of the mansion behind us.
No one spoke.
My eldest brother sat across from me, looking out the window with that bored face he always had, like nothing in the world could interest him. The second eldest fiddled with his cufflinks, pretending to be too grown-up to notice anything. And my father—my father sat straight, as if the world were watching him even inside this moving box, his jaw set like stone.
I could feel his anger before he even opened his mouth.
Finally, he did. His voice was low, sharp, the kind that made the air feel colder.
"Akihiko. Do you have any idea how you looked out there?"
I blinked. "...Cool?"
The second brother snorted, quickly covering it with a cough when Father's eyes flicked toward him.
I sat up straighter. "I didn't do anything bad! I was just... I was helping. She was small. She was about to cry, so I helped her. That's what big brothers do, right?"
My father's head turned slowly toward me, his eyes narrowing.
"Big... brothers."
His tone was strange, like he was testing the words, like they tasted bitter in his mouth.
I nodded eagerly. "Yeah! Like with Yui. I'm her big brother, and she always stops crying when I'm around. So I did the same for her. That girl."
I didn't even ask her name. I didn't think I needed to. She was just... small. And I was big. That was enough.
Father's jaw tightened. His face was calm, but something underneath twitched—just for a second. A tiny crack, like the mask slipped and showed something raw, something I didn't understand.
"You embarrassed the family," he said, his voice still even but colder now. "Dragging her across the hall like a servant, shoving food in her mouth like an animal. That is not how a Mamiya behaves."
I crossed my arms, puffing my cheeks out. "I didn't embarrass anyone! She was fine. She even ate it. See? That means I won. She didn't cry. That's... that's a victory."
"A victory."
"Yes!" I leaned forward, suddenly animated. "Big brothers protect their little sisters. That's a rule. If she's about to cry, I stop it. If she's small, I make sure she feels safe. I promised. I promised Yui I'd always be cool, that I'd always work hard, that I'd—"
"Enough."
The word cut through me like a knife.
Father didn't raise his voice. He didn't have to. His hand, resting on the armrest, twitched once, and his eyes... his eyes weren't angry anymore. They were worse. They were... tired. Heavy. Something like pain flickered across them, but it disappeared so fast I almost thought I imagined it.
I shrank back into the seat, my heart pounding.
The eldest brother cleared his throat. "Father, perhaps—"
"Silence," Father snapped, not even looking at him. The eldest brother froze, turned his face back to the window, and said nothing more.
The car was quiet again. Too quiet.
I hugged my knees to my chest and stared at the ceiling. I didn't understand. I was being a big brother. That's what I promised Yui. That's what I'll always do. Why was that wrong?
Father's profile, lit by the faint glow of the passing streetlights, stayed frozen. Only once, when he thought I wasn't looking, did his lips press together, tight enough to turn white.
I didn't say anything else.
The rest of the ride was just the hum of the engine, the shifting shadows outside, and the faint taste of sugar still clinging to my tongue.
The car rolled to a stop in front of the estate. The gates closed behind us with their usual heavy clang, like a prison locking shut.
I hopped out, nearly tripping because my legs felt heavy from all the food. The night air was cool against my sticky fingers, but Father didn't slow down to notice. He walked ahead, sharp and straight-backed, with my brothers trailing after him like shadows.
I followed behind, dragging my shoes against the stone path, half on purpose. No one turned.
Inside, the house smelled faintly of polish and faintly of nothing at all. Too clean. Too big. Our footsteps echoed down the hallway. Father dismissed the chauffeur with a flick of his hand and then disappeared toward his study, the doors shutting with a dull finality. My brothers vanished too, muttering about homework or sleep.
Just like that, I was alone.
I stood in the hallway for a moment, staring at the tall clock ticking steadily against the wall. Its sound filled the emptiness.
"...They didn't understand," I whispered.
A soft laugh bubbled behind me. Not mocking—familiar.
I turned, and there she was. Yui. In her little nightgown, hair mussed from sleep, clutching her worn plush rabbit in her arms. Her eyes were wide, curious, like she had been listening to everything.
"They don't get it, do they?" she said softly.
I grinned and crouched down so we were face to face. "See? I told you. Being a big brother is about protecting. Even if Father doesn't like it."
Yui's small hand reached out and grabbed mine, warm and real. "You're the coolest, Aki-nii. The coolest."
My chest swelled. The heaviness from the car, the coldness in Father's voice—it all melted away. She believed me. That was enough.
"I'll keep working hard," I promised, pressing her tiny hand between both of mine. "One day, I'll be strong enough that nobody can laugh at us. I'll protect you. Always. I swear."
The clock ticked.
And then a door creaked open down the hall. A maid appeared, bowing politely. "Young master, you should wash up before bed."
I turned back quickly—
The hallway was empty. Just me. Just the echo of ticking and the faint draft from the window.
I forced a smile at the maid and nodded, but my hand still tingled, as if Yui's fingers were wrapped around it.
The maid's bow was as precise as always, but softer tonight. Her voice had that kind of kindness you only use when speaking to a child you don't want to upset.
"Young master, shall I draw the bath for you and Lady Yui?"
I froze. My chest warmed at her words. Lady Yui. She said it naturally, like she'd seen her standing there. Like she wasn't just mine.
"Y-Yeah," I said quickly, puffing up with pride. "She's with me. Right, Yui?"
Yui nodded eagerly, rabbit bouncing in her arms. "I don't like cold water though."
I laughed. "I'll tell her to make it warm. Super warm. You'll like it."
The maid only smiled. "Of course, young master. I'll prepare it at once." She didn't even blink. Didn't even look confused.
She'd always been like this. Playing along. Never asking questions. Never telling me I was wrong.
I liked her for that.
We ate something light in the kitchen before bed—well, I did. Biscuits and milk. The staff had already set them out, and the maid poured two glasses, placing one in front of the empty chair beside me.
I beamed. "See, Yui? They remembered."
Yui swung her legs beneath the chair, humming as she lifted the glass. I watched her tiny hands tilt it to her lips, though the milk never lowered.
I didn't notice. Or maybe I didn't care.
Later, after the bath, after changing into pajamas, I lay in my wide bed with Yui curled against me, her rabbit squished between us. The curtains were drawn, but the moonlight slipped through the cracks, painting faint silver lines across the room.
Yui's voice broke the silence. "Aki-nii?"
"Mm?"
"Can we go to the beach tomorrow?"
I blinked at her. "The beach? Why?"
She grinned, showing her little teeth. "I wanna make a sandcastle. A big one. Bigger than the house."
I laughed, loud enough that the maid outside the door might've heard. "Bigger than the house? That's impossible. It'd collapse right away."
"No, it won't," she said stubbornly. "If you help, it won't. You're strong. You can make it perfect."
I felt something twist inside me. That word. Perfect.
I ruffled her hair, making her pout. "Fine, fine. Tomorrow we'll go to the beach. I'll make the biggest sandcastle anyone's ever seen. And I'll build walls so high, no one can knock them down. Not even Father."
Her eyes sparkled. "Promise?"
"I promise."
Yui squeezed my hand as if sealing the vow herself, then darted off toward the nursery with her rabbit bouncing in her arms. Her laughter trailed down the hallway like windchimes.
I stood there a moment longer, grinning stupidly, until the maid gave me a look that suggested I should get ready for bed before Father decided to add another lecture to tonight's collection.
"Yeah, yeah," I muttered, dragging my feet toward my room.
When the door clicked shut behind me, silence returned. Not the suffocating kind from the car, but the kind that felt like an open stage waiting for me to fill it.
My room wasn't what people expected from a child. The shelves weren't cluttered with toys; instead, they were lined with books. Thick ones. Some I barely understood, others I clung to like secrets. The crown jewel among them sat on my desk: Cyrano de Bergerac, with its creased spine and bent corners.
I hopped into the chair and flipped it open to where I'd left off. The words danced in strange, flowery rhythms, but I loved them. Cyrano's speeches felt like spells — clever, biting, ridiculous. He made the world bend with nothing but wit.
I didn't understand everything, not really. But I liked the way it sounded in my head. I even practiced sometimes, holding a pencil like a sword, swinging it through the air as I whispered:
"A great nose may be an inconvenient thing... but a man without courage is nothing at all!"
I laughed quietly at my own dramatics, then hunched back over the page.
On the side of the desk, a notebook lay open, half-filled with scribbles. My handwriting was clumsy, but the ideas weren't. I had diagrams of sandcastles — yes, sandcastles — complete with bastions, moats, walls, and labeled weak points. I'd been sketching them for weeks, ever since I first told Yui we'd go to the beach one day.
No ordinary sandcastle would do. I wanted fortifications. Defense lines. If waves were enemies, then I'd outsmart the tide. I'd already tested building methods in the garden with dirt and water from the hose, recording which designs collapsed fastest and which held the longest.
I tapped my pencil against the page. If I make the walls thicker at the base, they'll hold better. And if I angle the trench...
The words of Cyrano blurred into the diagrams of fortresses until both became the same thing in my head: poetry and strategy. Wit and defense. A knight and his walls.
And always, Yui's voice echoed in the back of my mind: Promise?
I shut the notebook gently. Tomorrow, we'd go to the beach. Tomorrow, I'd prove that promises weren't just words.
I glanced once more at Cyrano's bold lines on the page, then whispered to myself:
"Cool big brothers don't break their vows."
The clock ticked, the house breathed, and I bent back over my sketches until sleep pulled at my eyes.
The next morning, I woke to the maid drawing open the curtains. Sunlight flooded the room, golden and bright.
"Good morning, young master," she said with a gentle smile. "And good morning, Lady Yui."
I turned to the side. Yui stretched, yawning, rabbit still clutched in her hands.
"See?" I whispered to her. "Even she remembered."
Yui giggled.
The maid didn't flinch. She laid out two sets of clothes on the chair—my small shorts and shirt, and a tiny dress I recognized. White cotton, with faint lace at the hem. Yui's dress.
It had been folded away for years.
My throat felt tight, but I smiled anyway. "We're going to the beach today."
The maid only inclined her head. "Of course. Shall I inform the driver?"
On the ride there, Yui pressed her face against the glass, squealing at every passing tree. I laughed along, elbowing her gently, though my brothers were nowhere in sight. They'd stayed behind.
The maid sat quietly in the front. Once, she glanced at me in the mirror, her eyes flicking—just for a moment—toward the empty space beside me. But she didn't say anything.
She never did.
The beach was wide and endless. Waves lapped at the shore, and gulls cried overhead. I kicked off my sandals and grabbed Yui's hand, tugging her toward the sand.
We built castles until my arms ached, piling bucket after bucket, shaping towers and bridges. Yui's laughter filled the air. She clapped every time I made the walls taller, shouting, "More! More!"
I didn't stop. I couldn't stop.
Because every time I looked at her, every time I saw her eyes light up, I remembered my promise.
To always be the coolest big brother. To always protect her.
And no matter how heavy the sand, no matter how high the towers needed to be—I'd build them. I'd build until my hands bled, until my arms broke.
Because that's what big brothers do.
By the time the sun dipped low, the castle was enormous, bigger than anything else on the shore. Yui threw her arms around me, giggling.
"You did it, Aki-nii! It's perfect!"
I hugged her back, chest burning with pride. "See? I told you. If I'm here, nothing will fall apart."
But when I looked up at the maid standing in the distance, her face was unreadable. Her eyes were soft—but not happy. Almost pitying.
And when I blinked, just once, the castle seemed smaller, crumbling at the edges.
I held Yui tighter, refusing to look again.
Later on...
The ride back was quiet. Yui leaned against me, rabbit tucked beneath her chin, eyes drooping with sleep. I stroked her hair absently, staring out at the road as the car swayed gently.
For a moment—just a moment—I let the silence press too deep.
And in that silence, I felt it. That hollow echo where laughter should've been. That truth I never wanted to touch.
I know.
I've always known.
Yui isn't here. Not like this. Not in the way the world insists on counting.
But if I admit it out loud, if I let myself believe it, then what am I supposed to do? Smile at breakfast, study, laugh, move on as if nothing happened?
Could I really go on like nothing?
The thought burned, sharp as glass.
I tightened my grip around her, pulling her closer, burying my face in her hair that smelled like sunlight and sea salt.
No. I won't. I can't.
Because the moment I move on... Yui will really be gone.