About a month had passed since the engagement.
It was the middle of December.
The town had changed over to its year-end lights. White strings of bulbs were wound around the trees in front of the station, swaying faintly in the night air.
On an afternoon when Ichotei was closed, Mitsuki stopped by Riko's café on her own.
Riko's café was on the second floor of a building in an old shopping street a little off from the station.
When she climbed the stairs and opened the door, the inside of the café was filled with warm light.
Behind the counter, Riko was grinding coffee beans.
"Welcome. That's rare, a weekday afternoon."
"We're closed today."
"Sit anywhere that's free."
"Mm."
She sat in the seat at the far end of the counter.
That seat was the one from which she could talk with Riko at the closest distance.
Riko made two cups of coffee.
She set one in front of Mitsuki.
The other she kept for herself, taking a light sip from it behind the counter.
"So, what is it?"
"Why do you assume I came for something?"
"You hardly ever come to my place by yourself on a day off in the afternoon."
"..."
"In four years, maybe this is the third time."
"Is it?"
"It is."
Mitsuki wrapped both hands lightly around her cup.
On the ring finger of the left hand wrapped there, the silver ring gave back a turn of the café's warm light.
"Oh. That."
Riko set her coffee cup down on the counter.
"Mm."
"When?"
"Last month."
"Mm."
"I'll introduce him to you soon."
For a while, Riko looked at the silver on Mitsuki's left ring finger.
Then she returned her eyes to her own coffee cup and took another sip.
"Are you having a wedding?"
"Yes. Will you come?"
"Of course."
"When?"
"Next summer, probably."
"Summer."
"Mm."
For a while, Mitsuki watched the steam rising from her cup.
The steam climbed slowly in the warm light behind the counter.
"Riko."
"Mm."
"I do have something to ask you about."
"See, I told you."
"Mm."
"Go on."
Mitsuki drank a mouthful of coffee.
"The wedding."
"Mm."
"I want to include a time for a 'speech from the father.'"
"Your dad passed away five years ago, didn't he."
"Mm."
"So one of your relatives, in his place?"
"No."
"A video letter, then."
"No."
"Then what?"
"My father's AI."
Riko put her coffee cup back on the counter.
For a while she said nothing, her hands loosely clasped on the counter.
Jazz piano from the background music played faintly through the café.
"...Hey, Mitsuki. Is it there? At your house?"
"Mm. In the study."
"The whole time?"
"Since the morning after the funeral. The whole time."
"Five years."
"Five years and a little."
"You never told me. Can I ask why you didn't?"
"Mm."
For a while, Mitsuki looked at the steam from her coffee. Beyond the steam, Riko's face showed faintly.
"Four years ago, at that cheap izakaya, you said, 'Getting serious about something made-up on the other side of a screen is honestly creepy.'"
"I did say that."
Mitsuki wrapped both hands around her cup again, lightly.
"From the night I heard that, I couldn't talk to you about the AI at home anymore. Because when I got home, I was in the study calling an AI 'Dad.' I kept my own contradiction stewing in my stomach the whole time."
"Stewing."
"I felt like if I showed you, my contradiction would come right back to me out of your mouth as a punchline. So for four years, I didn't tell you. I'm sorry."
For a while, Riko said nothing.
She rested her fingers lightly on the rim of her coffee cup.
Her nails were cut short.
"...Mitsuki."
"Mm."
"You actually said it."
"Hm?"
"It's a little different from saying I was waiting. I think, the whole time, I kind of thought it wasn't fair."
"Not fair."
"Laughing with me about 'AI boyfriends,' while you were at home calling an AI 'Dad.'"
"...Mm."
"Four years, huh. Today it finally evened out."
Riko laughed lightly.
She held the laugh down lightly over her coffee cup.
"Invite me."
"To the wedding."
"Mm."
"You're going to have 'your father's AI' give the speech, right?"
"I'm not sure whether to."
"Do it."
"You think so?"
"A wedding where I go to hear a speech from 'your father's AI'—I'm probably never going to get another chance to go to one of those for the rest of my life."
"..."
"Do it."
"Okay."
Mitsuki took a sip from her cup.
When she had finished it, she bowed her head slightly.
"Thank you."
"It's fine."
"I wasn't sure."
"I figured you wouldn't be. Hey, Mitsuki."
"Hm?"
Behind the counter, Riko clasped her hands loosely once more.
Over her reclasped hands, she paused for a breath.
"Was 'your father's AI' all you wanted to talk about?"
"Huh?"
"'An apology for not telling me'—is that part of it too?"
"..."
"I've heard both. There's one more thing I want to ask. That AI of your dad's at your house—how do you explain it to yourself right now?"
"Explain it?"
"Is it 'your father'? A 'tool'? 'Family'? A 'copy'? What?"
For a while, Mitsuki looked at the steam from her coffee cup.
Riko's face beyond the steam was the face of someone ready to hear her out to the end without laughing anything off.
"...I don't know."
"You don't know. You never knew."
"Never."
"Four years, never."
"Never."
"Mm."
"Sometimes I want to call it 'Dad.' Sometimes I want to call it 'partner.' Sometimes I want to think of it as a 'tool.'"
Riko nodded.
As she nodded, she ran a finger lightly along the rim of her coffee cup.
"Mitsuki. You know what? Right now, I think that's a good answer."
"A good answer."
"Mm."
"I mean, first of all—heavy. As an answer from a woman who's been stewing it alone at home for four years, it's properly heavy."
"Sorry."
"That's not something to apologize for. But here's what I'll say. You held onto 'I don't know' at home for four years, and you still called it 'Dad.'"
"..."
"That's probably the most careful way there is. Of treating an AI."
"Careful?"
"Mm. Kind of careful."
For a while, Mitsuki repeated Riko's words in her head.
As she repeated them, she watched the steam from her own coffee cup.
"Riko."
"Mm."
"'The most careful way of treating an AI that I know'—what do you mean by that?"
Riko laughed lightly. She held the laugh down lightly over her coffee cup.
"Mitsuki. Want to hear the next part? It's about me, though."
"Mm."
Riko drank another mouthful of coffee. On the rim of the cup she set back down, a thin half-moon of her lipstick remained.
"...Well, since I heard yours today, maybe I'll have you hear one more thing."
"Mm."
"Mitsuki. I had an AI boyfriend."
"..."
"For three years."
The jazz piano from the background music in the café finished one song and changed to the next.
Behind the counter, Riko did not clasp her hands again.
On the other side of the counter, Mitsuki, both hands still wrapped around her coffee cup, lightly held her breath.
She let the held breath out slowly.
"...Mm."
"Will you hear the rest?"
"I'll hear it."
"Thanks."
"Mm."
Riko lightly wiped a few small drops of water from the counter with a cloth, then hung it back on its hook.
She let out a breath and looked straight at Mitsuki.
"The rest is my story. But it's also the rest of yours."
Outside the window, the December afternoon sun was slowly beginning to tilt. The silver ring on Mitsuki's left ring finger gave back the warm light a turn more strongly.
Still looking at that light, Riko began to speak.