“Spot the difference?”
“Exactly. You know my right eye can see certain… unusual things, right? When you ran over there just now, I noticed something shift for a split second. I don’t know what it signifies, but I’m sure it’s nothing good.”
Bingying looked completely lost. “Are you saying someone deliberately made the classrooms on both sides look exactly the same?”
“You’re half right. In my opinion, this isn’t as simple as a physical arrangement. It’s more like mirror symmetry.”
“So, they’re one hundred percent identical? Like the world inside a mirror and the world outside of it,” Bingying said, a spark of understanding in her eyes.
“Precisely. From what I’ve read, each grade in this school should have twelve classes, from 1 to 12. But now, only classes 1 through 6 remain. Classes 7 through 12 are nowhere to be found. Perhaps they didn’t disappear. Perhaps they’re hidden behind an ‘invisible mirror,'” I explained.
“Wait, wait. Let me get this straight.” Bingying pressed her fingers to her forehead. “According to your theory, what we’re seeing isn’t the complete school building? Because there’s an ‘invisible mirror’ in the middle, the other half of the building is just a mirror projection of our side?”
“That’s about the gist of it.”
“But isn’t that just too bizarre? How could anyone possibly do that in reality? If it’s a perfect mirror projection, why didn’t my reflection appear when I walked over there?” Bingying tried to argue.
“Now that witches and sorcerers have been proven to exist, do you really think common sense still applies?” I retorted.
“Er…” Bingying was instantly speechless.
“The reason your reflection didn’t appear is probably because we’re outsiders, independent of this space. That allows us to pass through the mirror, in and out, without being affected. To be honest, I don’t fully understand it either, but we can run an experiment to verify it.”
“An experiment? What do we do?”
I stepped back into the fifth-grade, class 6 classroom and pulled out the wooden chair at the desk closest to the door in the back row. “Alright, could you please go over to the other side and see if the chair in this exact spot has changed?”
“I see, so that’s how we can check.” Bingying immediately ran over and then dashed back, her face alight with a mixture of surprise and excitement. “Reporting! The chair on the other side shows signs of being moved, too!”
“Then until we find other clues, let’s operate on this hypothesis,” I said with a nod. “Next, just as I said at the beginning, we need to find something different, shatter the ‘mirror,’ and get to the area behind it.”
“But if it’s a mirror image, how can there be any differences?”
“No, there must be a flaw somewhere—a single point of difference that serves as the foundation for this entire mirrored world,” I stated with conviction.
Bingying’s eyes started to glaze over again. Clearly, what I was saying was a bit much for even a top student like her to grasp.
“Bingying, have you heard of dimensional space?”
“The zeroth dimension is a point, the first is a line, the second is a plane, and the third is the three-dimensional space we exist in, right?”
“That’s correct. And above that is the fourth dimension, a space incomprehensible to humans.”
She just stared blankly.
“Don’t get too hung up on the term ‘mirror world.’ The ‘mirror’ is just an abstract concept I used to help you understand. Our world doesn’t actually have something like that; a person can’t just walk into a mirror. What I’m calling a mirror world is, in fact, a four-dimensional space.”
“Four-dimensional space… I remember that’s one dimension above the third?”
“Exactly. Infinite points form a line, infinite lines form a plane, infinite planes form a solid, and infinite solids form a four-dimensional space. If I’m not mistaken, the other side and this side are actually the same object.”
“But…”
“I know what you’re going to ask. The reason we can’t see each other is that we’re in different places. That’s right—this half of the school building is a single object existing in two places simultaneously. Sounds impossible, doesn’t it? But it’s possible in the fourth dimension. Just like a two-dimensional being can only move on a flat sheet of paper, we in the third dimension can bend and connect that paper, allowing the 2D object to instantly reach the other side. Wormholes work on the same principle, using a higher dimension to traverse space. And it’s thanks to you that I figured this out, Bingying.”
“Thanks to me?”
“That’s right. If I were alone, I doubt I would have uncovered the truth of this place. After all, the fourth dimension is almost impossible for us to imagine. It was only by having you here, providing a point of comparison, that I could reach this conclusion. Does that make sense now?”
“…” Bingying thought for a moment, then decided to give up. “So, in short, it’s just like you said before. We just need to find the difference between the two sides, right?”
I gave a wry smile. “It’s okay if you don’t understand. Since this is a fourth-dimensional space, we, as three-dimensional beings, shouldn’t be able to reach it. The fact that we’re here means there must be a flaw. Let’s call it a 3.5-dimensional space, somewhere between the third and fourth? By the same token, this ‘mirror world’ must also be imperfect. There has to be an object within it that, like us, belongs to the third dimension and cannot be projected. It’s the medium that allowed us to enter in the first place.”
“But where would something like that be?”
“Normally, as beings of a lower dimension, we couldn’t touch anything in a higher dimension, which would make it easy to spot the difference. But since we’re in this 3.5-dimensional world, our own dimension has been elevated, allowing us to interact with the objects here. For now, the only way is for one of us to take one side. We’ll take pictures of every classroom with our phones, then meet up to find the discrepancy.”
After all that, Bingying finally understood my plan. We split up, and another hour or so passed before we met back in the office where I had been earlier. Through the window, the sun was tinged with red, gradually sinking behind the western mountains, casting a nostalgic, weathered light over everything. And yet, if we were to walk to a classroom on the other side, we would see the exact same view. What a strange and fascinating place.
“Tianchen, you’re really amazing,” Bingying said suddenly, as we sat together comparing the photos on our phones.
“Why the sudden praise?”
“Because you always stay calm no matter what happens, and you solve puzzles so quickly. You’re so smart, always saying things that sound profound even if I don’t understand them… Compared to you, I’m just holding you back,” she said, her voice trailing off.
“You’re not wrong.”
“You’re not even going to deny it?!”
“Because someone else has said the same thing to me before,” I replied calmly.
“Someone else… Was it your ex-girlfriend?”
“Maybe… I’m not sure,” I said noncommittally.
“Hmph…” Was it my imagination, or did Bingying sound a little jealous? “And then?”
“I said, ‘Since you’re so self-aware, why don’t you just leave?'”
“That’s so mean! Tianchen, you’re so mean!”
“I admit I wasn’t the easiest person to talk to back then. But she wasn’t scared off. She said, ‘A monster is a monster because it’s been away from people for too long. As long as someone stays by its side, even a monster can have a human heart.'”
“I don’t get it. But… no matter what, I’ll never leave you. You’re the one who saved me and gave me a new life. I’ve never even thought about anyone but you.”
“Yeah, yeah, I know. Another troublesome one to deal with,” I said, patting her head in the tone one might use with a child.
“You’re just going to brush off a girl’s hard-won confession like that?!”
“Yes, yes. If you have time to talk nonsense, you’d better get back to work.”
Bingying grumbled a bit but obediently lowered her head and resumed her task, which thankfully saved me from being exposed.
That was close. She almost saw me blushing. At the end of the day, I’m still a hot-blooded teenage boy. Being told ‘you’re the only one’ by a beautiful girl like her… what guy wouldn’t react? Seriously, this girl usually acts like a proper young lady, but after everything we’ve been through, she seems to have awakened some kind of obsessive side. On the surface, she’s the same as ever, but whenever we’re alone, she becomes childish and clingy. Is this her true nature? Or has she mistaken gratitude for love because I saved her a few times?
‘When she made her wish all those years ago, the hidden meaning was to see you again. As the Witch’s Seed matured, those feelings became harder to conceal. So don’t you worry. I can tell you with certainty that she truly likes you. Just go for it.’
“I see. So, why have you appeared now?” I tilted my head. Where Bingying had been sitting was now a grinning, silver-haired loli dressed in the same nun’s habit as when I first met her. In her place, Bingying had vanished. Yet, I wasn’t worried. My last encounter taught me that I was in some sort of illusion. The real Bingying was still sitting safely beside me.
“Oh, nothing much. Just came to give you a little reminder. You’ve found quite an interesting place, you know,” the girl said in a slow, loli-like voice. Her appearance was that of a small child, but she spoke like an adult, creating a peculiar sensation.
“A reminder? A reminder of what? Is there danger?” I was instantly on high alert.
“That is…”
“Guu…” With a small gurgle, the loli face-planted onto the table. “…Hungry…”