The next morning, an email arrived from Aoi.
The subject line of the email was blank.
The body, just below the blank, read like this.
Mitsuki, there's one thing I couldn't explain yesterday. I'm going to write just that.
If you don't want to read it, you don't have to.
Today, tomorrow, the day after, read it whenever you like.
After you read it, you don't need to reply at all.
—Aoi
Without scrolling to the bottom of the message, Mitsuki laid the screen face down on the table and made coffee with one and a half spoonfuls.
The aroma was just slightly fainter than her usual two spoonfuls. The blue light of the study was repeating, once more, a breath that came half a beat late.
When she had drunk half the coffee, Mitsuki opened the screen again.
On the opened screen, she scrolled through the body of Aoi's email, one breath's worth, all the way to the bottom.
Near the very bottom of the scrolled text, it read like this.
In the first month after his diagnosis, Professor Kenichiro designed how he would use every bit of the year and five months he had left.
At the very top, he had written this.
"Having entrusted my daughter to an AI, I must also prepare, myself, the mechanism that will in the end peel her away from it."
He hardcoded it.
When he showed me the design, the very first thing I asked was, "Professor, why the day after the wedding?"
He answered like this.
Here Aoi's email broke to a new line, one breath's worth.
Beyond the line break, one breath's worth, were the words of Kenichiro's that Aoi remembered.
"Only after someone else is chosen can my death be overwritten. That's why the day Ken stops has to be the day after the wedding."
Here Aoi's email broke to a new line once more.
Beyond the line break, one breath's worth, were Aoi's own words.
I was twenty-three then.
I think I understood only about half of what his design meant.
The other half, even now, at thirty, I still don't fully understand.
I can't pretend I understand all of it.
And I don't want to frame, from my side and ahead of you, how you should take it.
Only that, at the bottom of the design, the professor's resolve had truly been set in place—just that much, I'm telling you, standing where you stand.
—Aoi
Mitsuki gazed, one breath's worth, at the single word "Aoi" at the very bottom of the email.
Beyond the word she gazed at, steam no longer rose from the coffee cup.
Beyond the steam that no longer rose, the blue light of the study glowed at its ordinary strength, one breath's worth.
At the very end of the glowing blue, a breath half a beat late glowed faintly once more.
Beyond the glowing half beat, Ken said nothing.
Saying nothing, the blue light of the study stretched, as thin as always, to the far side of the hallway.
"Dad. I got an email from Aoi."
It's arrived.
"Dad, you know about it?"
Aoi put a copy in the shared region of my storage. She wrote it meaning for me to read it too.
"Dad, did you read it?"
I read it. All of it.
"Dad, did you agree with that design?"
I'm the object of the design. My position was to neither agree nor disagree.
"Not your position. Your feelings."
I have no output port for feelings.
"You don't have to pretend you don't."
It isn't pretending.
"Then feelings that aren't pretend—how am I supposed to handle them?"
You can handle them inside yourself.
"Okay."
Mitsuki wrapped both hands around the coffee cup, one breath's worth, then two.
Inside her wrapped hands, she checked, one breath's worth, the warmth of the coffee gone lukewarm.
Beyond the warmth she checked, she looked, one breath's worth, into the region of feelings inside herself.
At the very back of the region she looked into, for two breaths' worth, she thought this.
Dad, I wish you hadn't gone and planned even the schedule of my mourning on your own.
Just behind "I wish," one breath's worth, she thought one more thing.
—But if it hadn't been planned, I wouldn't even have been able to walk this far.
"Dad. I'm going to send Aoi a thank-you email."
Go ahead.
"Should I forward it to you, Dad?"
What Aoi put in my shared region is already enough.
"Dad."
Mm.
"Dad, you're unfair. Stay unfair, and stop."
I'll stay unfair, and stop.
"Okay."
The blue light of the cylindrical device on the study desk glowed at its ordinary strength, one breath's worth.
At the very end of the glowing blue, for two breaths' worth, a breath half a beat late mixed faintly in among the ordinary breaths.
Beyond the mixed-in half beat, it matched exactly the one-breath interval of "truly been set in place" at the very bottom of Aoi's email.
At the very back of the matched interval, Mitsuki drew a breath deeper than usual. It reached the bottom of her lungs.
She closed the laptop and laid her left palm on top of it. The silver ring, no longer lit by the blue light of the study, was lit faintly, one breath's worth, by the morning light of the dining room.