It was one afternoon, around the time Makoto's user count was about to reach two hundred.
The Gotanda office hadn't grown one step bigger than that first single floor. One long table, three chairs. All that had increased was the number of displays on the table. The sense that the company had started to run was measured not in rent but in screens.
On a secondary screen in one corner, a sumo broadcast was playing. It was one of Mio's few hobbies.
"Sumo," Mio said to no one in particular, watching a bout, "is built so that match-fixing happens easily. That's why it's a wonderful sport."
"...If someone from the association heard that compliment just now, they'd faint, Mio." Aya looked up from her color proofs.
"I'm not disparaging it. I'm talking about design," Mio went on flatly. "Eight wins gives you a winning record, and your ranking and your pay go up. Seven wins and eight losses, you drop. So for a wrestler who goes into the final day at seven and seven, everything rides on the last bout. But for an opponent who's already secured a winning record, a ninth win isn't worth much."
"So only one side is desperate."
"Right. The stakes weigh heavily on one side only. So today you give up the win, and get paid back somewhere else. It's almost harder not to fix the match."
"That's a nasty thing to say."
"I'm not the nasty one. The numbers are." Mio followed the back of the wrestler who had won the bout with eyes that held no warmth. "Wrestlers at seven and seven on the final day win eighty percent of the time. Even though their expected win rate, calculated from past matchups, is under fifty percent. They're paying back debts in wins."
"So. Your hobby is watching that?"
"Not just watching. Calling it. Saying who's lending and borrowing wins and when, from the sequence alone. Even when you count wins, they aren't necessarily real. Because stakes distort the numbers."
"...Okay, then let me ask," Aya said, leaning forward, half amused. "Is there match-fixing? This tournament?"
Mio didn't answer right away. On the screen, the next wrestler was throwing salt. Then she smiled, just slightly, at the corner of her mouth.
"That's a secret. I'll only say that since problems came to light in the past, the distribution has been normalizing."
At that rarely seen smile, Aya lost her words for a moment.
Next to them, Mikoshiba was gripping a stopwatch. His thumb came down the instant the wrestlers rose for the charge, and stopped it the instant one stepped out of the ring. The seconds from the initial charge to the decision, he wrote in his notebook, bout by bout. It had started as Mio's hobby—she'd let slip, "Match-fixing probably shows up in the timing too. Sumo that follows a script is oddly short, or oddly long," and started timing them. He had taken it over from her. Having Mio's fingers spent on grunt work like this cost the company far too much.
"...Hey, Boss. What've you been doing with that this whole time?" Aya eyed the stopwatch in his hand dubiously.
"Measuring." Mikoshiba didn't take his eyes off the screen. "It was originally Himuro's hobby. If she presses the button herself, her more advanced work stops for that long. Someone with free hands can take it over for her. Rational, isn't it?"
"A CEO glaring at a stopwatch, timing sumo one bout at a time—a real paragon of rationality," Aya said in a monotone. Mikoshiba didn't crack. "It's efficiency."
Mio processed it as a superior managing a subordinate's hobby. As resource allocation, if anything, it was correct. She didn't notice that the thumb ticking off the seconds was beating the same rhythm more meticulously than any wrestler in the ring.
"Hey, Boss. This one's rejected."
Aya peeled one sticky note off the wall of them and stuck it back onto Mikoshiba's desk. It was a rough of Makoto's feed screen.
"Put 'Recommended for You' higher. Make it bigger. Time on site goes up—who said that?"
"The data says it," Mikoshiba answered, without even looking at the note. "Put recommendations higher and users stay longer. That's a fact."
"That's exactly why it's rejected."
Aya rolled up the sleeves of her men's sweatshirt. Mio's hands stopped on the keyboard. When Aya used that tone, it was usually worth listening to.
"The moment keeping people there longer becomes the goal, social media turns into an addiction factory. Kotoba was like that. Anger and anxiety grow the most. So you stack the posts that stir up emotions at the top. And people scroll till the middle of the night, angry the whole time."
Mikoshiba finally looked up.
"Makoto won't do that." Aya flicked the sticky note with a finger. "I'm not letting the loud ten percent decide what the other ninety percent get to see. I don't want to line up stuff that's just loud because the majority's shouting about it, like it's genuinely popular. That's the pillar of my design."
Next to the note she'd peeled off, Aya stuck two more notes side by side. Two tabs at the very top of the feed.
"So this is what I want to do." Aya poked the left tab. "Get rid of the single 'Recommended' at the top. Instead, two tabs. 'Trending' and 'Following.'"
"What's the difference between the two?" Mikoshiba asked.
"'Following' is only the people the user picked themselves. It just flows in chronological order. A shelf you decide on yourself, where the machine doesn't stick its hands in between." Aya tapped the right tab. "'Trending' is a window for peeking at what people out there are making noise about right now. But it doesn't pile itself onto the top on its own. People who want to look go and look on their own two feet. Both are designed so the loud ten percent can't squat at the top of everyone's feed."
Mio offered a quiet technical remark.
"I think we could add 'Recommended' too. With collaborative filtering."
"Oh?" Aya turned around. "Mio, what's that? Recommended is the thing I just rejected."
"What you rejected was a single popularity ranking for everyone, wasn't it. The kind where the loud ten percent monopolizes the top of everyone's feed," Mio answered flatly. "Instead, you swap it for a separate shelf for each person. Things that people 'similar' to you liked get recommended to you alone. It's just the machine taking over for word of mouth."
"Similar people, huh." Mikoshiba propped his chin in his hand. Whenever Mio's rapid-fire talk started, he always wore the look of someone determined not to miss a single word. "So how does that work, concretely?"
"It's a system that secretly goes around peeking into every shopping basket in town. It finds people whose baskets look like yours, and whatever else they picked up, it puts on your shelf too."
"It's convenient. But there's a price. The shelf gets too dyed in your color. Since it only gathers the tastes of 'similar people,' different things gradually disappear from view. A cozy little octopus pot."
"That's what they call a filter bubble, right?" Mikoshiba picked it up. "It's comfortable, but before you know it, you can't see a single person who thinks differently."
"That's why Aya's 'Trending' works," Mio said. "What's making noise right now outside your own bubble. Only the people who want to look can go and look. Opening that window first was the right call."
Aya grinned and wrote one more tab onto a sticky note. "See, Mio, you and I really click. Then it's settled. 'Following' is a chronological shelf you pick yourself. 'Trending' is a window you walk over to on your own to peek outside the bubble. And we add 'Recommended' to that—with collaborative filtering, as a shelf for each person. No more single popularity ranking for everyone at the top. That way, the ten percent who are only loud disappear from the top of everyone's feed."
"Your voice is five times louder, Aya," Mio said briefly, but didn't disagree.
Aya took a swig of canned coffee. "In the end it's all the same thing. Lining up stars that only got big because of stakes, like they're genuinely popular—that's what I can't forgive more than anything."
Mikoshiba watched the two of them over his coffee. Every time Aya got close to Mio, his gaze would invariably move to measure the distance. Mio didn't notice. Her estimate that Mikoshiba's real interest was Aya had long since settled in as the default value.