“You’ll start by going to the world next door. It’s one you’ve undoubtedly been to on a daily basis. And since it’s right next to us, they’ll almost certainly be doing the same test, so the parallel self that arrives in your place will be one that consented to the shift. That saves us needing to explain anything, so the return shift will progress smoothly.”
Two selves, consensually switching places. If we could make that a reality, there was truly no telling what progress we’d make next!
“Of course, this counts as a facet of your work, so it’s your duty as a researcher to take part in the experiment the other world is running too. If all goes well, they’ll gradually start sending you out farther and farther. By exchanging information and technology with other worlds, we’re hoping not just our field, but all of humanity will take a massive leap forward.”
The benefits to society were astronomical. The mere thought of it made me dizzy.
“Now, when doing this kind of work, you can expect to have downtime. Not like we do our research 24/7, right?”
“Some days it can feel like it though,” I commented.
“…Yeah, sometimes. My point is, if you optional shift to a parallel world, you can use the time you spend there to see if you can love that world’s Takigawa-kun. In return, your parallel self will come here and see if he can love this world’s Takigawa-kun. Why not try and see if you can handle every you loving your lover?”
When I told Kazune about this suggestion, we ultimately decided that both of us would take part in the mock trial. We would find out if we were capable of loving each other’s every last possibility, and if we could let those possibilities love us back. And a few days later, we were escorted into a room at the lab that we never had access to before.
In the center of the room was a large capsule designed for one person to lie inside. This, we were told, was the magnetic field generator that would trigger the optional shifts.
“I knew it,” I whispered before I could stop myself.
Back when I was a kid, when I parallel shifted to a world where my grandfather was still alive, I woke up in this very pod. Of course, it probably wasn’t literally the exact same one, but nonetheless, this reunion made me feel strangely emotional.
Director Satou Itoko, founder of the ISRI and imaginary science as a whole, referred to the machine as the “Cradle of Einzwach,” but the other researchers just called it the IP capsule. It was common for her to borrow a fanciful name from some dusty old work of fiction, while everyone else went with something more practical.
She explained the trial process to us as follows.
“First, the subject will climb inside the Cradle of Einzwach. Then, we’ll activate the magnetic field generator from outside. The magnetic field will force your body’s particles to spin on a different vector, thereby overwriting your IP and shifting you to a world that matches the new IP. That’s the basic overview of how it works. If we can resolve the negative effects of magnets on the human body and ensure the subject can return home to World Zero, it’ll open the door to authorization for a real clinical trial.”
“I notice there’s only one capsule…er, Cradle,” I commented.
“We can’t afford to make a ton of them. Do you have any idea how expensive this thing was to construct?”
Whatever figure I was imagining, there were probably a lot more zeroes at the end.
“Now, who wants to go first?”
“I will,” I said, immediately raising my hand. Kazune grasped my other hand with a worried frown. I gave her a little squeeze and smiled reassuringly. “It’s okay. Hang tight and I’ll pave a path for you to follow.”
“…Okay.”
She nodded without objection. Who are you and what have you done with my Kazune?! Just kidding. It was nice not needing to hide our relationship since everyone at the lab already knew about it.
And so Kazune and I took turns shifting. By participating in this mock trial, we were officially added to the research team, and whoever wasn’t currently shifting was instead taught how to operate the machine and read the gauges. We both got a little pay raise too—a bonus perk neither of us was expecting.
A few days after orientation, our first-ever shift trial was set to be conducted. These experiments were performed late at night, just to be safe. After all, if we shifted while our other self was driving a car or something, it could cause a major accident. I lay inside the capsule, suppressing my anxiety just enough to smile at Kazune through the glass. She nodded back slightly, then took her position at the console.
“Five, four, three, two, one… Shift: on!”
As the countdown began, I closed my eyes. The magnetic field only took a few seconds to activate, and after that, the shift itself happened in a split-second. Other than a hint of warmth in the air inside the capsule, I didn’t feel anything different. Then the glass door opened, and I was greeted by…the exact same people.
“Can you check your IP for me?” the director asked, without pausing to ask how I was feeling.
Nervously, I looked at my band. If the screen displayed 001, the shift was a success…but would it…?
“…001.”
“Success! Welcome, Takasaki Koyomi-kun from the world next door.”
And so our first-ever optional shift trial was a resounding success. Over the next month or so, Kazune and I traveled between different worlds; when we got there, we were always inside the same IP capsule, which meant all of our selves in all the neighboring worlds had had the same idea. That said, beyond an IP of 004, small differences became more and more apparent, like the position of the furniture in our rooms, or the cars we drove. In World 7, I had apparently shaved my head, which was refreshingly different from the usual. But what was most valuable to me personally was that I got to see other Kazunes doing these experiments right alongside me.
During my first optional shift, when the two of us had a private moment, we immediately showed each other our IP bands. Mine read 001 and hers was 000. The world next door was nearly identical to mine, so Kazune 1 fully understood what we were doing and why. Thus, the first thing we did was go to our usual karaoke lounge.
“Nice to meet you… No, it’s really not the first time, is it?”
“No, I imagine we’ve met without realizing several times before now—and we’ve had at least one conversation where we did realize.”
Yes, I certainly remembered that. Her twentieth birthday—the night our “first time” ended in failure. I could recall seeing 001 on her IP band that night.
“Feels weird, doesn’t it? To be totally honest, you don’t seem the slightest bit different from Kazune 0,” I said.
“In this world, I am Kazune 0. But yes, you don’t seem any different yourself.”
That much was to be expected, of course. The difference between our worlds was as trivial as what we’d eaten for breakfast. And naturally, I recognized the ring on her left ring finger. “Oh hey, it’s an aquamarine.”
“Yes, er… Well…I suppose I should thank you.”
“What brought that on?”
“You gave this ring to your Kazune as well, yes? So I figured I may as well thank you on behalf of all of us.”
It was such a bizarre feeling. Everything else was exactly the same, and yet the person in front of me wasn’t the same Kazune I proposed to.
“You’re still gonna marry me, right?”
“Of course. I mean, I want to. Is that not the whole reason why we joined this trial?”
“Yeah, and it’s your turn next, huh? Well, don’t sweat it. It’s really easy.”
“I’m not worried about the trial itself. It’s the part that actually matters to us. Finding out whether we can love the others—and allow them to love us in return.”
I nodded. Could we love our parallel counterparts? And could we accept those same parallel counterparts loving our beloved?
“To be totally honest… I don’t think I’ll have trouble with the first part. If you asked me to have sex with you, I’d probably say yes.”
“Yes, and perhaps I would. But the problem is…”
“The reverse, yeah. Back in my World Zero, I suspect your Koyomi is having the exact same conversation with my Kazune. The question is, can we accept that?”
“How are you feeling about it right now?”
It was a very difficult question to answer…but… “Personally, I have no intention of sleeping with you tonight.”
“Right.”
“That means your Koyomi most likely doesn’t want to sleep with my Kazune, so that’s a relief. But if I ever do make love to a parallel Kazune—all the while knowing my parallel self will make love to my Kazune—it’ll prove that I’ve truly accepted it.”
“And if you can’t make love to a parallel me, then…we can’t get married?” she asked me.
“Well… I think that’s a separate issue…”
“Ugh, this is so obtuse. I kind of wish they’d never discovered parallel worlds at all.”
“Yeah, I feel you. Before now, people could live happily, never knowing,” I replied.
Surely everyone had felt this way at least once since the advent of parallel worlds. But now that we’d discovered them, we had no choice but to live in a society reshaped by the idea.
Over the following month, the mock trials went reasonably well, with no major incidents. Kazune and I discovered that our relationship was a happy one in pretty much every other world. I still hadn’t slept with any parallel Kazunes, but I could feel my mindset slowly shifting.
What did bring about tremendous change between me and Kazune, however, was our tenth and final shift experiment.