My stepmother's burden is my ex-girlfriend.

Page 361

"Please use the older ones if possible."

With a feeling of anxiety and unease, I boarded the bus to my destination.

The planned itinerary for the third morning was to visit the Churaumi Aquarium.

Speaking of aquariums, it reminds me of the one I visited with Mizuto last year. But the Churaumi Aquarium is definitely a tourist attraction; it's a couple of sizes bigger than that one.

After taking photos in the square where the whale shark monument stands, everyone entered a building that was as spacious as a railway terminal and took the escalator downstairs.

As we descended the stairs, the azure sea unfolded before our eyes, and "Wow!" cheers erupted from the crowd. This place could be considered the main entrance to the aquarium, but it was also essentially a rooftop platform, offering a panoramic view of the vast ocean.

After you get off the escalator, turn right and you'll be at the entrance where your ticket will be checked. But this is actually the third floor. I heard that the recommended tour route for the Churaumi Aquarium is to enter from the entrance onto the second floor and then go down to the first floor.

"...So what are your plans next?"

I lowered my voice and asked the water bucket walking beside me.

There were no rules about splitting up, so everyone went with their own friends to explore the aquarium. But in an aquarium, which is supposed to be the perfect date spot, walking openly with Mizuto made me incredibly nervous. Mizuto, however, remained completely calm.

"I need to resolve this matter. It's not the spying incident; it's something else entirely."

"You mean the school trip handbook was stolen? What does that have to do with me? I just wanted to know what Asuhain-kun was thinking."

"In my deduction, the two things are closely related. Because Asuhain is the thief."

"what?"

An unexpected remark made me gaze at Shuidou's face.

Before I knew it, a large tank planted with various corals came into view.

Looking at the fish swimming in the tank, their colors a vibrant blue or bright yellow, as if painted, Shuidou said:

"To be precise, he was one of the thieves—to put it more bluntly, an accomplice."

"An accomplice...? Why would Asuha-in-san do that...!"

"I haven't thought of that yet, but I can roughly guess—so right now I just want to figure it out."

After passing the coral tank, we entered the exhibition area called "Sea of ​​Tropical Fish". Including students from Luolou, visitors thronged to admire the colorful fish swimming, which was quite the opposite of the tranquil and peaceful impression that aquariums usually give. The crowd was lively and crowded.

The water tank on this floor faces the roof, and sunlight filters through the water in the tank, casting a bluish-green glow that illuminates the walkway and the figures of visitors.

I moved among all of this, looking past the human wall at the tropical fish.

"...It's a rare opportunity, but it's a pity we can't see it more clearly..."

"Anyway, you can't concentrate right now, can you?"

Shuidou was considerate of my feelings when he spoke.

"You can come another day. You can also invite Minami and Asuhain along."

"……Um."

Actually, if that day ever comes, I originally wanted to come with Mizuto. Because this rare trip hasn't allowed us much time alone together.

However, now I think it would be nice to come with Asuhain and the others—boyfriends… a few close friends… there are so many people I want to travel with. When did I become so happy? It's unbelievable.

We walked around the huge water tank and into a narrow passageway leading to the next section. The sunlight streaming in from the tank was blocked, making the space as dark as a movie theater corridor.

Halfway there, I saw familiar figures. It was a group of female classmates from my class, the same group that was late for the assembly yesterday evening—the three of them were walking and laughing happily.

"May I bother you for a moment?"

Mizuto caught up with them and went up to chat.

The three of them turned around, looking somewhat surprised.

"I-Is there something you need, Irito-san...?"

The girl standing in the middle spoke on behalf of everyone, her tone revealing obvious confusion.

I was also confused. When I heard Mizuto say he was going to investigate the case of the handbook thief, I thought he would go and question Yoshino and the others—

"Excuse me, could I borrow your travel guide? I need to look something up, but I can't find it right now."

"Handbook? Uh... this..."

The three of them looked at each other with troubled expressions.

What's going on...? Why do you feel embarrassed?

The next sentence from Shuidou answered my question.

"It got stolen, didn't it?"

The three of them gasped in unison.

Stolen...? These girls' travel guidebooks were stolen too?

Facing the three people who were frozen in place and unable to speak, Mizuto seized the opportunity to continue:

"Don't be so wary, I won't harm you. Actually, I already have the suspect's name in my mind—to confirm, I'd like to see the manual you're carrying."

The manuals you're carrying with you right now? What do you mean? Didn't you just say they were stolen?

Shuidou turned to me, and said, "My mind is a complete mess:"

"Didn't I say it before—'They said it themselves'?"

"Uh...you mean the time we went to question Yoshino and the others?"

"right."

It's about what happened yesterday morning. Mizuto did say that—but he deliberately misled me and wouldn't tell me what he had figured out until the very end.

"The girl who testified at the time claimed that 'because all four people's travel brochures were missing from the room, she thought they had been stolen.' But she also said that 'when she got up in the morning and checked her bag, she immediately discovered that it had been stolen,' and that she didn't even need to check everyone's luggage to know that someone had stolen the brochures."

After he pointed it out, I realized something was wrong. When I was looking through my luggage and found my travel guide missing, I would generally assume it was lost—not immediately suspect it had been stolen.

"In other words, the situation was such that she only checked her luggage and discovered it had been stolen. What kind of situation would that be—I just want to get one possibility."

"that is……?"

"The situation where 'my travel guidebook has been switched'."

"ah……!"

As soon as I called out, all three girls looked embarrassed.

Indeed, if a travel guide has been replaced, it is clearly the work of someone else—that is, it has been stolen.

"But...aren't everyone's travel guides supposed to be the same? How would she know they were switched? Was it because the cover had her class printed on it, and hers was replaced with one from another class—or was there a note in the guide itself?"

"If their handbooks are replaced with those from another class, they can easily tell the teacher, since anyone can tell that they've been switched. But if it's a handbook from the same class, the teacher won't be able to tell if it's been stolen—because the teacher can't control what annotations are made inside."

"You made a note...you mean that's the thief's purpose?"

"At least I only want this possibility."

Everyone had the same version, but the school trip handbook, which seemed to have no value to be stolen, was stolen—it turned out that the thief wanted the notes in the handbook, that is, the information added to the handbook?

"I suspect that the travel guidebook that was switched and left with must have also been marked with notes. And these notes were written with a ballpoint pen or something similar, so they can't be easily erased."

At this point, Mizuto turned to the three girls who had fallen silent.

"That's probably why you got the meeting time wrong yesterday, right? After all, the time was crossed out—"

Yesterday's lateness—Mizuto actually became suspicious over such a small matter. He suspected that these three, like Yoshino and the others, had their travel guides switched.

After exchanging glances, the three whispered a few words to each other and then nodded slightly.

"……All right……"

The girl standing in the middle said, as if sighing.

"Since you've already seen through so much, there's no point in hiding it anymore... Is mine okay?"

"No, if I could, I'd like to see everyone's manuals."

The three of them each took a brochure from their bags. Mizuto took the three folded brochures handed to him and said, "It's too dark here, let's move forward a little."

The five of us walked through a dark passage and entered an area with several individual water tanks set up against the wall.

Near the entrance to the area, there's a jellyfish with countless slender tentacles hanging down like a beaded curtain, resembling a Cthulhu mythos. Judging from the accompanying description, its name seems to be "Bobo Jellyfish."

Shuidou avoided the crowd gathered in front of the individual sink and walked to the wall, opening the travel brochure they had given him.

"……I see."

"What? Oh, I see?"

Shuidou showed me the open travel brochures one by one.

Just as Mizuto said, there were several places in each manual where someone had crossed out the text with a ballpoint pen. At first glance, the crossed-out text seemed to have no pattern or common ground... and there was nothing suspicious about it.

"What's the point of swapping out an ordinary, unremarkable manual?"

"If you erase the text, you can't write anything on it anymore, right?"

"Annotating the text...? You mean drawing circles or crosses?"

"Yes. Suppose the stolen travel guide had these kinds of annotations—marks? Marks in various parts of the text, and if you connect these words together, it will..."

"...to form a complete sentence?"

After I used my reasoning skills to say this, Mizuto raised one corner of his mouth.

So that's how it was? The culprit stole it using a travel guidebook—

"A closer look reveals that all three manuals have text that has been crossed out without exception."

Before my thoughts could reach their destination, Mizuto spoke first.

He opened his own travel guide—a pristine copy without any annotations—and compared it with the three guides the other party had given him to confirm which words had been crossed out.

"Adding them all up... if we broaden the scope a bit, we can divide them into three types."

Then Mizuto showed me the travel brochure and pointed out every single word.

The text points out that the culprit who switched the travel guides did not want Yoshino or the girls to make any marks.

"--'He'".

"-- 'Reason'".

"── 'household'".

Kanji, hiragana, katakana, and even homophones like the number "一" (one) – none were omitted.

The characters that could represent these three words have been completely erased.

Iri-ho.

Needless to say... it is our surname.

"Why...why...?"

Why do you want to erase our surname—my surname?

Considering the entire sequence of events, the message conveyed by this travel guide is—

"They used travel guidebooks and played with coded communication using marked text."

Mizuto said calmly.

"It's like passing notes in class. Since we can't use cell phones now, we use this method of communication instead. And I suspect that the gossip you're deliberately passing around in this way is—"

Mizuto's unfathomable gaze followed the three people whose travel guide had been stolen.

"—Yui's boyfriend. Am I wrong?"

The three of them looked away and fell silent.

My...relationship partner?

Could it be... what I said when I rejected the confession...?

"After all, this is a hot topic. You've publicly stated that the other person is someone from our school, so it's not surprising that they would want to meet during the school trip if they're even in the same grade. So they used the travel guide to play a spy game, trying to gather relevant information."

Mizuto said, "I knew it would be like this." He closed the three travel brochures and stacked them up.

Now I understand—no wonder Yoshino didn't want me to know the travel guide had been switched. Thinking about it now, they weren't exactly welcoming of my arrival back then…

"I'm...I'm sorry..."

Upon hearing one of the girls' timid apology, Mizuto handed the neatly folded travel brochure back to them, saying: