"Almost 100 years ago, someone exclaimed that a detective story must have as its main focus the resolution of a mystery; a mystery whose elements are clearly presented to the reader at an early stage of the work, and whose nature is to arouse curiosity, a curiosity that is satisfied in the end. And for that reason, he created a series of rules for what at that time were considered games, these are known as Knox's Decalogue. These rules were very important for the development of mystery novels during the Golden Age of Detective Fiction. Currently, its use is quite debated, with purists saying that these rules are untouchable, while the most open-minded allow themselves to alter some of them or look for legal loopholes in their writing, which is why is important that each author understands these rules and decides which ones they really want to use and to do so, we will present them below:

1. The culprit must be mentioned in the early part of the story, but it cannot be anyone whose thoughts the reader has been able to read.

2. All supernatural or preternatural forces are prohibited during the course of the story.

3. No more than one room or secret passage can exist.

4. Poisons not discovered until now cannot be used, nor can any device that needs a long scientific explanation at the end.

5. No person of Chinese nationality can appear in the story.

6. No accident should ever help the Detective, and he should never have an inexplicable intuition that just happens to be right.

7. The Detective himself cannot have committed the crime.

8. The Detective cannot use any clue that has not been immediately presented for the reader's analysis.

9. The detective's assistant must not hide any thought that passes through his mind, and their intelligence must be below that of the average reader.

10. Twins, and doubles in general, cannot appear unless the reader has been thoroughly prepared for them."

Prologue: In the Park of Technology, the first crime was creating it.

The hooded boy with green hair who was reading that excerpt from a book ends up closing it, making a loud sound, the people in the room look at him strangely, as he begins to speak. - The Detective is finally at his full potential, so I hope that we can all work together to find the hidden culprit among us. - Not counting the body, apart from the boy, 8 other people were gathered in this place. Surely he was addressing them, but who were they to begin with? Apparently, they are winners of a contest that allowed a total of 8 people to come try this amusement park. The particularity of this park was its lack of human workers, everything being manipulated by an AI, but suddenly everyone noticed how the lights were turned off from one moment to the next, and the exits and communications with the outside world were cut off. This does not mean that they are fully trapped, the monitoring team must have noticed that the security cameras have been turned off, so it should not take long for them to send someone to check manually. The problem, however, would come when everyone went to gather, and a woman with several hours of sleep lost in the form of dark circles exclaimed out loud that someone had died. That is the explanation why everyone is conveniently here.

Analyzing the room where they are, it seems to be a circus, all the people are on the circus stage itself, decorated with some flags and drawings of what could be the different parts of the show. The famous corpse is at the center of all this, fallen on its back to the ground with a bullet hole in its head as it faces away from the entrance. Apart from the pool of blood under the body itself, there is nothing else that stands out in the place, the sits are evidently empty, and although the entrance to the dressing rooms is also here, everyone else is scattered around this room, scared, worried, or concentrated because of the murder in front of their eyes. Despite everything, the Detective need to continue their investigation, but since the body is unknown to them, they have to try to uncover its identity first. Thinking about that, the green-haired man speaks. - I'm sorry to disappoint you, but it seems I don't know the victim, would anyone here be able to help me with it? - In response to the hooded man's plea, a hooded woman with several bandages over her body responds, that is the same woman who reported the body in the first place, and that is who he was indirectly referring to. - Sunne Schwarz. He was my boss... I say it was because it seems he is no longer with us.

The chatty boy looks away at the body, while a woman in a lab coat who was previously worryingly silent behind him approaches to examine the corpse. After listening to what was said by the girl who seems to have not slept a wink in weeks, the Detective seems to have confirmed that the corpse is really dead, so the hooded man speaks again, bringing his left hand to his chin. - That's right, it seems like he has left this world... That makes things easier, there is one less person to suspect.

A small white-haired boy in a sports tracksuit who was also there timidly raises his hand as if asking for a turn to speak, and as soon as everyone seems to notice him he begins to speak. - I d-don't think you should be talking like that... P-please show some more respect. - It is obvious who he is referring to, so the victim of his words smiles cynically before responding. - I'm sorry, the little kid must not know who I am. I will do the honor of introducing myself to all of you. I am "The Detective", the one whose word is absolute at a crime scene! My name is not relevant, so you can refer to me as "N"!

- Silence. - The woman with black hair and amber eyes stands up after apparently having investigated the body on her own and seems somewhat upset with the hooded man's attitude. - You're just a kid not taking this seriously, you should learn something from people who are really underage in this place. - The scientist was referring to the boy who spoke previously, and to a redhead with what looks like a Japanese priestess cosplay who was hiding behind her holding her lab coat. "N" smiles again, staring at the woman before answering, it's hard to classify what kind of look this is, but if I had to say, it's close to the condescension of seeing someone who hasn't accepted their place in the world. - Come on, come on, don't start being all aggressive with me. Those are just formalities. Have you discovered anything investigating the body, dear ally? - Annoyed, the woman responds - Tsukamaeru Kanjou, call me Tsuka. Apparently, the cause of death was cranial perforation by a firearm. I found the bullet near the entrance, and I already did the favor of comparing it to the wound.

- Ah, good, good! Kanjou-san, it seems that you have not told any lies, since your deduction is the same as that of the great detective "N". It would have been a problem to catch someone lying so early. - After the Detective announced the results of their investigation, they began to look around the room to analyze everyone present. - It seems like we're all there. As we all know, eight people had the pleasure of entering to try this amusement park ahead of time. And if I'm not mistaken, they warned us that there would be two members of the Circus staff who would be preparing things for their performance at the opening ceremony. This means that one of us must be the culprit...

"N", Tsukamaeru Kanjou, the red-haired girl, the hooded girl, a blonde woman, an adult man, another green-haired man, a blue-haired girl, the white-haired child, and Sunne's corpse. These seem to be the characters chosen to participate in this mystery. - W-why does it have to be one of us? - The red-haired girl, still scared enough to not speak very loudly, seems to say something that not everyone can hear, although the Detective is clearly among them.

- The answer is obvious, the murderer must be one of the characters presented in the first part of the story. However, if that explanation does not satisfy you, the script reason is quite obvious, no one other than us could enter the place without the AI detecting them as an intruder, but after the light went out, it was also impossible to enter or exit because of the closing of the doors. - For the first time, "N" seems to say something that increases the respect that the rest have for him since his argument seems solid enough, but the redhead is not completely convinced. - B-but what if there is some kind of passage? O-or maybe he forced entry... I-I don't think it's safe to say something like that so easily...

- Tsukumo, we'll go investigate those possibilities later, okay? - The girl who had her name revealed nods slowly and holds on to the woman who just spoke to her. The hooded woman also seems to want to add something to the Detective's statement. - I agree that it is too early to say that one of us is indeed the murderer... Even if the strange boy is right, you must admit that this may have been a trap from the beginning, the organizers of the event could be behind this... After all, they personally invited us to this park to perform on the opening day... - After the girl gave her conspiracy theory, "N" responded instantly wanting to clear up a doubt. - I've been wanting to know something for a while, but... You're part of the circus team, right? To be honest, it seems to me that you are the main suspect in this case. - After what was possibly considered slander, most viewers seem convinced that he is right, but the girl tries to deny the suspicions about herself as best she can. - Lucia Junoire, I am an acrobat who is part of the circus. Unfortunately, I cannot confirm my innocence without the security cameras, the good side is that I do not have to prove my innocence to you. I imagine the police will check it out when it finally arrives.

- If you really are innocent, I would not be so expectant of the police. Since the Detective is here, it's obvious that they will be unable to arrive until I solve it. Who knows how many victims it will take... - After what seemed kind of like a call to misfortune, one of the people who had been silent decides to raise her voice, speaking with a bombastic tone that is concerned with sounding fabulous at the same time that she hopes to be heard by everyone, that spirit is also reflected in her striking clothes, which denotes her status as a rich girl, in any case, she does not seem to have understood that phrase in the same way as the others, so responds in a way that no one would expect. - That's good! Having a detective with us will help us survive! I trust your abilities, honey, don't speak of yourself in a bad light again. I know it's hard to compete with my perfection, but you are also perfect in your own way... And if you need my support, I will give it to you! Use your talent with confidence, and reach for the answer to save us all!

- Madoka Marui, right? - Guided by the girl's emotion, and probably by the script's need to introduce all the characters while they are still in the circus, one more person raises his voice, a dark-skinned man in a red suit with a sharp gaze that would probably make you want to pin the blame for the murder onto him. - I once interviewed you, and I have to say that I am glad to have it here. Your ability to motivate and help others is quite calming, I hope you can help Mr. N find the culprit. - Even though he has not introduced himself, it is difficult to live in this country and not know this guy... With a name that honors his look, Mr. Alfons Rauch is a journalist like those who cannot be missing on a stage like this. - Oh, Mr. Rauch! - And once again, the pattern repeats itself, again it is a person who would be difficult not to know. It seems that she had not noticed that Rauch was there until now, which is normal considering the situation they are in, in any case, the name of this other character is Michaela, a very famous Diva among young people and adults alike, it would not be unreasonable to say that right now she is the most famous person in the world. She seems to be going to talk to Alfons, their conversation however is not of interest to the Detective, so the plot will continue to advance for the moment. - Well, I think we have progressed quite well with the introductions, however, I think there is still one person left... - "N" diverts his gaze towards the only person who still does not know his name, a boy just as green-haired as him with a sweatshirt and a carefree look, the boy scratches his head having been noticed, it seems that he was hoping to go unnoticed, but after a slight awkward laugh, he answers - Luki, Luki Fortune. - It seems that he considers that that is enough, so without saying much more he tries to remain silent again until a person shouts. - B-but what's wrong with you all!? - It's the white-haired boy, who seems a little angry at how everyone has forgotten the fact that there is a corpse in the middle of the room. It must surely be a strong shock for someone so small, but the rest of the personalities in the story are indeed too outlandish to really take the situation seriously, so it's normal for him to act so bothered. - Sorry, little Plamik. I was following the necessary procedures in a story of this style, but you're right that we should get to work. I'm confident that I've done enough research in this scenario, according to Knox's Eighth Rule, I'm confident that I haven't missed any clues. Lucia, there are the dressing rooms back there, can I come to take a look? - Tsuka gets up, it seems that she is also interested in going to the dressing room, and Tsukumo is still a little worried about not being close to her. Luki and Madoka also seem interested in investigating, so they accompany "N" while Lucia guides the Detective to the dressing room.

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As soon as they all arrive, Tsuka prepares to investigate throughout the room with Tsukumo, Luki only stays in the corner, it doesn't seem like he really has any interest in investigating, but he surely came to stay informed about the case. Lucia, for her part, tries to explain a little what this place is. - This is the circus members' dressing room, it is quite big because there are usually more of us. - Lucia doesn't seem particularly happy to mention those other people, but "N" seems to take a special interest in this. - What is the reason that only the two of you have come?

- It was the boss who decided it. We were called here to give a presentation on opening day, which would be a week after the tests if everything ended up going well. In my opinion, it was obvious that this was all going to go wrong... Letting an AI control an entire park... It seems like they are just crying out for us to be dominated by machines. I wasn't particularly interested in coming, but the boss... He loves to bother me. The park staff believed that it was better to bring as few people as possible so that nothing leaked about the Park, so they told the boss that he could only bring one assistant for the preparations, and he decided to bring me just for that reason... - Sighing, the girl has a somewhat thoughtful expression, it looks like she didn't like the situation she was in at all, raising the Detective's suspicions. Even if she says she has an alibi that can be proven on camera, it's currently impossible to do that, so suspecting her is pretty safe. Madoka however raises her fabulous voice to talk about something different with the poor girl. - Ohoho, you seem a little depressed, girl. I understand the Boss wasn't very good to you, huh? I know how it feels, really... But you can't let something like that cloud your talent... You gotta be strong, girl! You were an acrobat, you said? I'm sure you're a fabulous one at that, and you have to believe that too. Even with all the difficulties, if you can go out on stage and show everyone how perfect you are, isn't it worth it?

- Yes, maybe you're right... I'm sorry I'm being so blue, let's continue with what I was saying... - Before she has the chance, Tsuka interrupts, showing a box she has found, the contents are... Worrying. Inside the box is a gun and 2 bullets, however... There are several other slots, where it looks like there should be another gun and about 8 additional bullets, however... - They're not there, uh... - N admires Tsuka's discovery, looking at her with some suspicion. - Can I trust that you didn't just take it?

- Don't be dumb, the murderer seems to have already used the gun in the previous crime. That being the case, I would not want to draw attention to this evidence, so you would not know of the existence of it. Lucia, would you mind explaining? - Everyone focuses on looking at Lucia, who proceeds to talk about the supposed weapon. - It's a gun that we use in our shows, but... Yes, as you suspect, it is authentic. It comes in pairs, but it seems like the killer has the other one... I'm sorry for not saying anything, it's not exactly legal to have them, and I didn't expect him to actually have them since they were hidden. But I suppose it will be necessary to tell you about it... We only have those two pistols, and we also only have a total of 10 bullets. Up to 8 bullets can be placed in one of these guns, and it is impossible to reload until they are all gone. Because they're for our shows, it is made like this for dramatic effect... - Trying to check if his words are true, Tsuka opens the ammunition and puts the bullets into the gun, and after closing it, she really can't open it again. - Yes, it seems to be true... And I haven't been able to find another gun or bullets...

- So, it's time for the Detective to solve this case! - "N" speaks loudly, making even the people who stayed behind able to hear him, Madoka accompanies his shout with excited applause, and "N" returns to the stage after saying that, understanding the gesture, those who were in the dressing rooms follow him. Once they arrive, Plamik, Alfons, and Michaela focus on "N", attentive to what he has to say, so he begins to speak. - Taking into account the position of the body and the bullet, the victim had to be killed from the front while his back was at the entrance. In that case, the murderer had to have been in the dressing room, right where the gun was... A gun hidden inside a box, which in turn was quite hidden... It seems pretty crazy to me to say that anyone could have simply entered the dressing room just because, and upon finding the gun, having gone out with it to kill Sunne as soon as he saw him enter. - N takes a short pause there, so everyone can give their opinion, and Tsukumo seems to take that opportunity. - What if he had gone in to try to rob the circus? It would be logical that this way he would find the gun...

- I expected you to say that, but... Hehehe, it's impossible, just by taking a look anyone would see that the room was tidy, and unless the thief knew exactly what he was looking for, which is unlikely, he would have messed it up looking for what to steal. - Tsuka raises his hand, accompanying the deduction of "N" with an observation. - I can confirm that there was nothing out of place, except for the gun. It was obvious that everything was in order. - "N" shows his characteristic cynical smile, fixing his eyes on Lucia. - Therefore, our only suspect must be the person with a motive to kill his boss, the person with the knowledge of where the gun was... And who is using an unverifiable alibi to buy time... - Everyone in the room is smart enough to understand who he is referring to, so no one asks any questions about his argument... It seems impossible to disprove right now, so Madoka applauds. - Excellent! A perfect deduction, I knew that trusting you was not a bad option, Detective.

- Anything to say, Lucia? - Lucia doesn't seem angry, or surprised, or even indignant... It seems like she expected this development, so she just... - Unfortunately, without the security cameras I have no way to prove my innocence. At least, not right now, but there are things we should check before you all jump on me... - Many seem confused about what she is referring to, and the one asking the question is Tsukumo - What do you mean? - Responding to the girl who seems to be gaining confidence, the scientist is the one who speaks. - It means looking to see if anyone has the gun right now. Well, I don't think she simply means that... Checking if there really can't be external interference is also a way to prove that there is more to this case than it seems, and finally, if we could restore the electricity somehow, we could look at the cameras... - Having been understood perfectly, Lucia nods. - You can search me if you want, I don't have any gun...

- Well, then it is the Detective who must investigate. - "N" begins to approach Lucia, however, Tsuka stops him. - Wait a minute, you could be an accomplice or something like that. I won't let you investigate who has the gun. - "N" smiles, he seems a little upset that they have stopped him. - Speaking of guns, Kanjou-san, did you keep the one we found in the dressing room? - Tsuka, without any expression, answers the question. - That's right, for personal defense.

- Gosh... How dangerous, right? What if you were an accomplice? - All the spectators begin to whisper among themselves, and Alfons raises his voice. - Are you saying that there is another gun besides the murderer's? It seems to me that we should seriously discuss who should have it, not just leave it to her, no offense. - Tsuka sighs, and leaves the gun on the ground, Alfons approaches to try to open the magazine, but is unable, so "N" explains to him what is happening, and after that, he looks at Tsuka. - Let's do the following, since we are both quite distrustful, the two of us can check everyone, and then we check each other. This way we will know that no one has the murderer's gun. - Tsukamaeru thinks for a few seconds, before accepting. And so, one by one they went looking for the gun, unfortunately, no one had it on them. - It would have been too easy, hm... I wonder where the gun is... - Thinking out loud, N throws out a question that makes everyone think about it, and Tsukumo is the first to answer. - In our rooms, perhaps? - Tsukamaeru caresses the little girl's head, accepting her suggestion and speaking to the rest. - We should divide into groups to investigate everything we need to.

- Isn't dividing into groups usually a bad idea in murder movies? - Alfons raises an important question, but Tsuka waves his hand to deny it. - That's just in the movies... If we have everyone controlled in large groups, it's the best to solve this. To go to the rooms and check the light you must do so in the East Wing of the park. Tsukumo and I will stay in the West Wing to see if anyone from outside can enter here.

- What if you want to stay here to erase some evidence? Or maybe the gun is somewhere around here? - N questioned Tsuka, receiving a look of contempt and a response from her. - Plamik, stay here, please. - Plamik looks surprised but doesn't seem to refuse. Tsuka questions if the rest have a problem with it, but no one says anything. And after a while of discussion... Alfons, Lucia, and N will go to the East Wing to try to fix the light. While Michaela, Luki, and Madoka investigate the park hotel in the same wing, trying to find the gun. As for the so-called "Detective Gun" by N, because they are escorting Lucia, it was decided that his group would carry it. N wanted to do it, but Tsuka wouldn't allow it, so it's Alfons who seems to have it right now. And with this, the story begins to move forward.