The only reason someone would steal something as meaningless as a guidebook was to obtain the extra information written inside. That had been the culprit’s objective.
“The guidebooks most likely contained information that the victims wrote down. Something that couldn’t easily be erased. Maybe something that’d been written in ink,” Mizuto said, looking at the three girls who’d clammed up. “That’s the reason you three got the time wrong yesterday and came late, right? The part about the meeting time had been blacked out.”
Wait, he was thinking about this all from such a trivial incident? That’s all he needed to suspect that these three had had their guidebooks switched out like Yoshino-san’s group? The three of them once again looked at each other before whispering among themselves and then finally slightly nodding in agreement.
“Okay...” The girl in the middle sighed. “If you’ve figured out that much, then there’s no reason to hide it anymore... You good with mine?”
“If possible, I’d like to see all three of yours.”
Then, each of them took out their guidebooks and placed them in Mizuto’s hands.
“It’s kinda dark here, so let’s go somewhere brighter,” Mizuto said.
We moved as five down the path until we got to an area with tanks on the walls. Right next to the entrance to the area, there were countless long tentacles that looked like curtains of beads hanging down. The jellyfish almost reminded me of Cthulhu. Looking at the plaque there, I learned they were apparently habu-kurage, a type of box jellyfish.
Mizuto approached the wall, avoiding the crowds around the tanks, and began opening the guidebooks.
“I see...”
“You figure something out?” I asked.
Mizuto showed each one of them to me. As he’d said, each of them had been marked by a pen. Where they’d been marked seemed random. There didn’t seem to be a pattern...or at least that’s what I thought.
“Why would anyone switch out the guidebooks?”
“If someone blacked out the characters, you wouldn’t be able to write on them anymore, right?”
“By writing on it...do you mean like marking them with circles and x’s?”
“Yeah. What if the stolen guidebooks had been marked up like that? If you pick out each marked letter, then...”
“It spells out something?”
Mizuto smirked, showing off his mind for mystery solving. That’s what the culprit was aiming for? They stole the guidebooks that had hidden messag—
“If you look closely, each of these guidebooks have the same letters marked,” Mizuto said before I could finish my thought.
Mizuto took out his clean guidebook and compared it with the other three to confirm what the blacked-out letters had been.
“Broadly interpreting it, there are three types.”
And then Mizuto showed me the guidebook and pointed at each letter that the culprit desperately wanted Yoshino-san and the other girls to see.
I. Ri. Do. Whether they marked kanji, hiragana, or katakana, they’d carefully spelled out “Irido.” It was unmistakably our last name.
“Wh-Why...?”
Why is our name—my name there? But judging by how this is going, then the message the guidebook is trying to spell out is...
“They used the guidebooks for cryptographic communication,” Mizuto said calmly. “It’s like passing around notes in class. Probably using it in lieu of a phone since we don’t have ours. My guess is that if they’re going through the effort to share information, then it has to be about...” Mizuto’s gaze showed no emotion, but it was piercing through the three who’d had their guidebooks stolen. “Who Yume’s dating. Right?”
The three of them looked away and clammed up. Who I’m dating? Like, the identity of the person I say I’m dating when I turn people down?
“It’s been a target for rumors anyway. You’ve made it obvious that it’s someone at the school, and if it’s someone our age, then it wouldn’t be crazy to assume that you’ll be meeting with them sometime during the trip. They’re probably using the guidebooks as a way to collect information and spy on you. Figured as much...” Mizuto said, closing the three guidebooks and stacking them on top of one another.
It makes sense. This is why Yoshino-san didn’t want to reveal that their guidebooks were swapped—not stolen outright. Now that I think about it, it felt like she wasn’t super happy that I’d come to her room.
“S-Sorry...” one of the girls quietly apologized as she accepted the guidebooks back from Mizuto.
“I’m not mad or anything, and I doubt she is either,” he said, shooting me a glance. “She hasn’t been shy about the fact that she’s seeing someone, so I can’t blame anyone for being curious. If anything, it’s her fault for making things so mysterious in the first place.”
“Hey! Who’s side are you on?!” I protested.
“But,” Mizuto continued, “I know you guys had no ill intentions, but it doesn’t feel great to know that people are sniffing around my stepsister’s business. Just be more careful in the future.”
After giving back their guidebooks, Mizuto didn’t even so much as say goodbye before turning his back to them and leaving.
“You’re a little angry, aren’t you?” I quietly asked after catching up to him.
“Nope. You heard me. You’re in the wrong here.”
Really? I could sense that there was some kind of societal politeness and rigidity in his voice and actions. I got the feeling he’d acted like this as well when guys had begun swarming around me at the start of our first year. I could feel myself smiling a bit. I considered poking him in the ribs, but I noticed that the girls were still watching, so I stopped myself. Instead, I decided to tease him a bit.
“You really emphasized the ‘sibling’ part back there, huh?”
“What? Did you want me to say, ‘Leave my woman alone’?”
“No way. I’m just surprised that someone who hates conversing with others as much as you can be so deliberate with your words.”
“Yeah. I’ve grown a bit.”
“And who do you have to thank for that?”
I looked at Mizuto as he fell silent, still looking forward. Even so, I knew exactly what he was thinking. He was probably going to put on airs and say that it was all for Higashira-san’s sake, but he most likely stopped himself because that wasn’t something that he should say to his girlfriend. I intertwined my fingers behind my back, feeling a new spring in my step.
“As your big sister, I’m so happy that my little brother’s grown into such a cool young man.”
“We have something more pressing to talk about.” Perhaps sensing that he was at a disadvantage, Mizuto forcefully changed the conversation. “So, we know that Yoshino’s group and those three girls were using the guidebooks as a way to pass notes to each other. If that’s the case, then what was the goal of the person stealing their guidebooks?”
“Uh...to see what they were writing?”
“If so, then stealing the guidebooks on the first night was way too early. It’d be better to wait until the second night when the girls had gathered more information. Besides, with a simple code like that, they could probably just glance at it and understand without having to go through the effort of stealing it.”
“True... So then...”
I thought back to the condition that the guidebooks they’d had were in. Because of all the blacked-out words, they couldn’t be used for codes anymore.
“To stop people from looking into me?”
“Yeah, that’s probably why.” I was slowly beginning to understand what was going on behind the scenes. “The girls in our class are pretty much divided into two forces,” Mizuto said, sticking up two fingers like a peace sign. “The first group is Yoshino and her friends. They wanna know who your boyfriend is. The other group are the thieves—the people who want to get in their way.”
Apparently, it was right to assume that the guys weren’t involved at all. According to Mizuto, the information he’d gotten from Kawanami-san had been correct. Now that I had a clear picture of all the pieces in play, I lightly stroked my chin while trying to put everything together.
“I think...I might have figured it out,” I said.
“Figured what out?”
“The mastermind behind the guidebook theft.”
“Me too,” Mizuto said, grinning. “There’s only one girl in our class who could do it so naturally.”