She pressed play.
At first, about two seconds of silence.
Then her father's voice. His voice from when he was alive and still young, with no noise mixed into it.
"...Yui. Can you hear me?"
Mitsuki pressed back into the chair once more. She pressed, but there was almost no strength left in her back.
After her father's voice came a strangely long silence.
After that silence, there was a response.
A different voice.
A woman's voice.
But the voice was somehow stiff. The ends of its sentences were flat as paper, and there was no sound of breath between them. It was the stiffness of a machine trying to copy the way someone spoke, and not yet having copied it all the way.
...Yes.
At first, Mitsuki couldn't tell whose voice it was.
Her father's voice gave a soft laugh.
"Yui. I'm sorry. With my skills, this is still as far as I can bring you."
...
"Even so, that's all right. Just listen."
Yes.
Even so, at the very core of its outline, it resembled someone she should have known only from photographs. It was the kind of resemblance that had not yet managed to trace that someone's way of speaking.
Even so, Mitsuki knew. At the nape of her neck, where her hair began, she went cold.
Her father's voice went on.
"Mitsuki said she hated me."
...
"She's seven. A seven-year-old girl told me she hated me."
I see.
"She said, 'Papa doesn't listen to me.' Her logic was out of order, so I told her to sort out what she wanted to say before she said it."
...
After a long silence,
I think that was not a good thing to do, came the reply, flat, like something out of a textbook.
Her father was silent for a while.
"Yui."
Yes.
"Am I not suited to being a father?"
No answer came back. The silence went on for a long time.
Her mother's voice didn't answer. Her father said nothing either.
—Seven.
Mitsuki remembered.
It had been at the breakfast table. Partway through, she had put down her fork and said, "Papa doesn't listen to me." Then she had said "I hate you," too. Her father had eaten his own breakfast in silence.
Who her father had been telling about it that night—Mitsuki learned that for the first time more than ten years later.
She opened another file.
The date was much more recent. A date at the end of the summer when Mitsuki was sixteen.
"Yui."
Mm.
"...You've gotten much better at talking."
Have I?
The end of that first reply was different from before. It rose, just slightly. There was the sound of breath. It should have been the same woman's voice, yet that paperlike stiffness from before had vanished somewhere.
"They found a disease."
...
"A rare one. They gave me a year and a half. Two years at most."
I see.
"How should I tell Mitsuki?"
You don't need to tell her. Not until the very end.
"...That's cheating."
It's all right to cheat.
"All right to cheat?"
That girl looks strong, but at the core she's still five years old.
—At the core, Mitsuki repeated at the back of her throat. Her mother couldn't possibly have known that.
The sound of her father drawing breath.
"Yui. I'm going to leave her all alone."
Mm.
"So that she isn't left alone, I have to leave something behind."
Leave what?
"I don't know. The house. Money. —That alone probably won't be enough."
Then leave yourself. As much of you as you can.
Her father was silent for a long time.
Then he murmured something. She couldn't make it out. She couldn't, but the words that came after it were clear.
"—I'm a researcher."
Mitsuki stopped the playback.
Having stopped it, for a while she looked at the time display in the corner of the laptop screen.
Another file. The date, another year again.
"Yui."
Mm.
"A former student of mine refuted me in a paper."
Oh my.
"The one they called a genius. He published a paper rejecting the core of my research, naming me directly."
Did you read it?
"I did."
And?
"...He has a point."
You hate admitting that kind of thing, don't you?
"...I have no choice but to admit it."
Her mother's voice laughed again.
When it comes to your research, you really are clumsy.
What is he saying?
"That my AI is half-finished."
Half-finished.
"Saying it isn't complete unless it works together with people amounts to admitting that the AI on its own is incomplete. That's what he wrote."
And you don't admit that?
"I do."
Then that's fine, isn't it?
"He doesn't admit it, and he's trying to build a finished form with AI alone. He writes that with objective data from hundreds of thousands of samples and an enormous AI model, it will surpass the subjective memory of a single human being."
Oh my.
"He's leaving me behind."
...
"I couldn't stop him."
For a while, her mother's voice said nothing.
You were fond of him, weren't you?
"..."
That genius boy. You took him under your wing at the lab, didn't you?
"...I admit it."
It isn't being criticized in a paper that hurts, is it. It's being left behind by him that hurts.
For a while, her father said nothing.
"—Yes."
...
"I know."
Mitsuki didn't know the student's name.
She didn't, but it was probably that man. The man whose name alone Riko had spat out that morning.
Mitsuki stopped the file. There was still something else she had to hear.
She looked at the file list again.
There was just one file with an extremely long running time.
Where the other files ran ten minutes, twenty at the longest, that one ran twenty-five.
Mitsuki rested the cursor on it.
"Dad."
On the desk, the starlike light of the darkened device was watching her.
It wasn't reaching Ken's ears. It wasn't supposed to be. Even so, Mitsuki gave one more small bow of her head toward that light.
"Just one more. I'm going to open it."
She clicked.