Her 'lab' smelled cleaner than before. Sharp, sterile, like she'd just wiped every surface down even though the shelves were still crowded with jars, glassware, notebooks, and old stains that would never come out. 

The clock on the wall read just after four. Afternoon sun cut through the curtains she hadn't fully drawn, slicing the room into bands of gold and shadow. Dust drifted in those beams, slow and aimless, like it belonged to some other time.

I leaned against the doorframe. "So, what are we even doing here?"

Sumireko didn't answer. She was already lining up bottles on the center desk, her movements sharp and sure. A petri dish sat waiting in the middle, spotless, like it was about to host something fragile.

Merry walked a little closer, hands clasped loosely behind her back. "You look way too serious for a prank."

"It's not a prank," Sumireko muttered, unscrewing a cap. "Just watch."

I sighed and stepped in, careful not to knock over the neat rows she'd set up. The glass clinked softly as she measured and poured — potassium bromate, sulfuric acid, malonic acid, drops of ferroin that gave it a reddish tint. Finally, sodium bromide. The liquid settled, still and ordinary.

"...That's it?" I asked.

"Not yet." She tilted the dish with a fingertip, then set it back flat.

For a moment, nothing happened. Just a pool of liquid reflecting the stripes of sunlight through the curtain.

Then, slowly, the center darkened. A deep red spot spread outward, bleeding into the surface like ink. It faded, only for a blue ring to bloom in its place. Then red again. Then blue.

Merry leaned closer. "It's breathing."

"It's chemistry," Sumireko corrected, though her voice softened. "Belousov–Zhabotinsky. The solution never settles, it just... keeps reacting. Patterns that appear, vanish, then come back again."

Red, blue, red. The dish pulsed with a rhythm that didn't belong to any of us.

I rested my palms against the desk, feeling the faint warmth of the sun through the wood. The ripples expanded, faded, returned. Not random, not chaotic. A steady beat.

Like a heart.

Each wave felt like a single pulse, born and gone before I could hold onto it, yet part of something whole.

"...You ever think," Merry murmured, "that it's like a heartbeat without a body? Just the rhythm, floating here, until it stops."

I blinked. "That's... kind of bleak."

"Not bleak." She tilted her head, the shifting colors flickering across her cheek. "Just... honest."

Sumireko snorted. "You two really can't help yourselves."

But even she didn't look away.

The colors spread, contracted, spread again. The room grew quieter, as if the reaction had set its own pace and everything else was falling in line.

The sun had dipped lower, its angle sharper now, throwing the shelves into longer shadows. Dust no longer glowed in the beams — just floated, dull and gray.

The dish kept pulsing, but weaker, slower. Red, then blue, each cycle fainter, like it had to fight just to appear.

"...It's dying," I said, before I could stop myself.

"Not dying," Sumireko corrected, though her voice had dropped. "Just running out."

The next ripple barely reached the edge before it broke apart. Another tried to follow, thinner, fading halfway. Then nothing.

The surface went still.

The three of us stood there, watching the silence spread in its place.The room was quiet except for the faint hum of the outside world — a car passing, a cicada calling too early for evening.

The dish sat ordinary again, flat and clear, but the rhythm still pressed against my eyes, like an echo refusing to fade.

Merry exhaled softly. "A heartbeat... already stilled."

Her words lingered in the air as the light crept further down the wall, slow and unbothered.

I glanced at the dish one last time. The afterimage of its rhythm still echoed in my eyes, though the liquid lay flat, ordinary now. No pulse. No color.

Just a memory of motion, fading even as I tried to hold it.