Neutrino

Here is the English translation of your piece, adapted in a Murakami-esque tone and rhythm:

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"Hey," she said that night. "Isn't it amazing how a single actor on stage can somehow play an entire crowd perfectly?"

"...Are you talking about someone specific?"

"No, not really. Just a thought. You get that kind of moment in music, too, don't you?"

She was a classmate from the music conservatory. Piano major.
She claimed to be from the seventh planet of the Orion star system, far away from Earth. Not for sightseeing. Not for invasion, either. "I just needed a little break," she'd said. Apparently, there's no coffee on that planet. No pianos, either.

"I sometimes think this world is made from just a single particle,"
she continued as she efficiently brought water to a boil.

"One particle, moving so fast it turns into everything-people, birds, or maybe even that dotted eighth rest at the beginning of a Scriabin piece."

Her words always felt a bit like music. The sound reached me before the meaning did.

"So this world is really a one-woman show," she said.
"Just one particle, playing all the parts."

I sat in the chair by the window and drew a deep breath of the night air.
In the distance, I heard the faint sound of a train-but it was probably only something from memory.

"What happens if the particle stops?"

"Well...maybe the world ends. But it won't stop."

"Why not?"

"Because if it did, it might realize it was alone all along."

She finished the drip slowly, and poured coffee into my cup.
She didn't touch her own.

-

Not long after that, she disappeared.
Quietly, almost gently-she just slipped out of this world.

It felt unreal, and yet a part of me thought, maybe that makes sense.
The things she said that night had the feel of a quiet reveal.

"This world is a one-woman show."
That phrase keeps returning to me.
It sounds like a line from someone else's script, but no-it was hers. I'm sure of it.

One afternoon, I put on an old record.
Partway through, the needle skipped just slightly.
And that brief silence-
it reminded me of the way she used to pause between sentences.

Maybe that one particle is still out there,
softly performing this world, note by note.

-The world hasn't ended yet.
The particle is still moving today.