As she looked at me—a being with the same face as her own—her voice was tense, cautious, and just a little bit hopeful.

I did as she asked. I went to the community center for the first time, met Ritsuko Hironaka for the first time, and made a roundabout apology—feigning Sunao Aikawa’s prickly personality.

Ricchan accepted it at once, and I returned home in triumph. My first success. Sunao had been waiting on tenterhooks the whole time, and when I reported in, she gave me a big hug.

That evening, before her parents got home, Sunao waved at me. When she said, “Bye,” my mind cut out.

The next day she called me again.

I had no memories of the time I was gone. But when Sunao called for me, it was like the pieces of my mind floated up out of some dark place, gathering together, taking shape again.

Each time she called me, I was dressed exactly like she was—like a mirror image. If she was in pajamas, so was I. If she was in new clothes, I had those on, too. When I vanished, these clothes vanished with me.

But if I vanished after I’d changed from pajamas to regular clothing, those clothes would fall to the floor where I’d been standing and the pajamas I’d started in would vanish with me.

Nothing lost, nothing gained. Whether by some god’s hand or otherwise, the rules I operated by remained consistent.

Sunao’s big eyes filled with joy and pride—she’d gotten her hands on a rare toy nobody else had.

“You know, something that looks like the real thing but isn’t is called a replica.”

She’d just learned this, and she seemed proud of her newfound knowledge.

When Sunao was little, she had boundless curiosity and tried all sorts of things.

How long could a replica stay out? If we split snacks, would we be twice as full? If we took the same test, would we get the same grade? If we played rock-paper-scissors, when would we diverge? She tried everything her developing brain could think of.

And what we discovered is that, biologically, Sunao and I were essentially identical—but there was a chasm between us, with a river running through it.

It wasn’t just the clothes I wore. Each time she called me out, I emerged with an updated copy of Sunao’s memories. But these were not my own experiences, and they never felt real. Recalling them was like squinting across a river to see the scenery on the far bank.

For instance, I didn’t remember the specifics of the variety show Sunao had watched the day before. That was because Sunao herself didn’t remember much of it.

Searching Sunao’s memories was like reading a book. Anything that made a strong impression on her was written in a nice, crisp font—easy to read. But sometimes the letters were blurry or the ink blotted, and it was hard to make out.

If something delighted Sunao or hurt her—anything that resulted in a strong emotional response—it came through loud and clear. But I only got a hazy version of anything she didn’t care about.

When you made a sandcastle on the beach, the next tide would wash most if it away. Still, a hint that something had been there would stick around. Because I didn’t get Sunao’s memories in real time, I was left patiently waiting to see what remains the tide would leave.

It was frustrating. I wanted to be more helpful to Sunao—I wanted to delight her and for her to shower me with praise.

As time passed and we grew older, I learned that Sunao was struggling to keep up with classes. And so any chance I got, I put my nose in her textbooks, reading them over and over, and sorting out the info in my head.

My memories, experiences, and injuries weren’t shared with Sunao. She didn’t need them. Sunao Aikawa was a complete person and didn’t require anything from her replica to fill her out.

I offered to help her study once, but she just looked at me like her eyes were made of glass.

“Nah,” she said. “Just take the test for me.”

I didn’t want to embarrass her. I did everything I could to get a good score.

At first, Sunao treated me like a close friend or a twin sister. She was a latchkey kid, so having me around helped her feel less lonely.

She’d call me out and give me half her cream puff. We’d read books together, watch cartoons, and laugh at them. No one else was allowed to see us together, so we were like two friends who shared a special secret.

But somewhere along the line, that went away. When Sunao called me, she’d tell me what she wanted and nothing else.

I smoothed things over when she fought with friends.

I got good grades on her tests.

I climbed mountains, ran marathons, even did the shuttle run for her.

All for Sunao, all for her. Everything I did was for her benefit.

I needed as much food, sleep, and trips to the bathroom as any other human—but if Sunao said, “Enough,” I’d just disappear, so she stopped caring about how I lived.

That’s why I’ve never eaten breakfast, though I’ve had a lot of lunches. The only snacks I’ve eaten were ones she shared with me. Splitting a cream puff didn’t make us twice as full, and these days, Sunao no longer shared them.

I’ve almost never eaten dinner. And I’ve never once had birthday cake.

In high school, Sunao stopped eating school lunches and started bringing her own. I was overjoyed. Her mother was very busy, so lunch was often made up of leftovers from last night’s dinner. Fried chicken pieces cut with kitchen scissors so they’d fit in the plastic box, or croquettes, or hamburger steaks. All full of flavor, all delicious.

And to fill the leftover space, she’d make new things: potato salad with sweet mayonnaise; mac and cheese on a piece of aluminum foil; bacon wrapped around bitter asparagus; or salted, hard-boiled eggs. To make it more delicious, the rice was often sprinkled with salmon crumbles, minced seasoned beef, or bits of egg and seaweed. Sunao had no idea how much pleasure I took in these simple toppings.

Lately, Sunao hated PE, but I liked it. She hated studying, but I didn’t mind it. If I hadn’t learned to like such things, life as a replica wouldn’t have been worth living.

***

Sunao called for me again the next day. She called me more often when her menstrual pain was bad.

That morning, she didn’t even have it in her to get out of bed. I put some water and painkillers on the cabriole-legged table and left the house.

I sat through class, ate lunch alone, struggled to keep my eyes open afterward, and then put my books away when the bell rang. Nobody would ever imagine a replica was here in Sunao’s place.

After school, I headed to the Literature Club. The door was always open—Ricchan dashed off to get the key the moment the bell rang.

I was always strangely relieved to find the door unlocked. Maybe it was because the doors to the house and Sunao’s room were always locked when I got back from school.

“Morning,” I said.

“And a good morning to you, Nao!”

Ricchan’s egg-like forehead gleamed, shining with sweat.

She looked visibly tired. Gazing through the open windows, I saw big billowy clouds floating overhead, as if announcing summer’s arrival.

A rusty fan was turning its head back and forth in the corner, but its gentle wafts of air weren’t nearly enough. Not only did it seem unlikely to cool us down, but I doubted the thing would survive the summer.

Officially, it was still the rainy season. The forecast had said it would rain today, but it had been just as sunny as the day before.

“If we had any funding, we could buy a new fan,” I said.

“I know! No use wishing for what we don’t have, though.”

Ricchan was lying with her head on the desk, glaring at the fan.

With a measly two members, the only thing the Literature Club could expect from the school was this tiny clubroom.

“Should we start collecting club fees?” she asked.

I gulped.

Unsurprisingly, replicas didn’t get an allowance.

I had Sunao’s memories of receiving things like dolls, lip balm, clothes, Blu-rays, and her smartphone, and I’d envied that. She let me carry her phone to school so classmates didn’t suspect anything—but it wasn’t mine.

I didn’t own anything, and I longed for something that was mine alone.

When I was little, I made a point of cleaning the bath or doing the laundry, and I collected a fee for my help.

I squirreled away the fifty-yen coins I received in a dusty tin. The container had once held Chocolate Crunch—a souvenir from a Disneyland gift shop Sunao had bought on a trip with her sixth-grade graduating class.

Sunao didn’t know I was using that can. In fact, I was pretty sure she didn’t remember it existed.

I’d piled up my earnings, never once using them. The can was pretty big, but it had filled up long ago. The rest was in a doubled-up supermarket bag I’d hidden along with the can deep in the upstairs hallway cabinet. Both were full of fifty-yen coins—heaps of them. I couldn’t let Sunao find out, so I didn’t dare lift the bag for fear of that rusty odor getting on me.

“How much do fans even cost?” I wondered aloud.

“I checked at the store, and old models are pretty cheap. They go for as little as a thousand yen.”

“Oh? That is cheap!”

Considering how much they were worth on a summer day, I’d imagined they were ten times as expensive.

“Then we only need to bring ten fifty-yen coins each!”

“Why fifty-yen coins?” Ricchan cackled.

Cleaning the bath, folding laundry, and running the vacuum each paid exactly fifty yen. The coins were small and cute—shaped like little donuts. As a kid, I’d treated each like a special treasure.

Just then, there was a knock at the clubroom door.