User:Chekhov MacGuffin/Internal rules in Detective Conan

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Although Detective Conan is a logic heavy detective fiction, it has many elements which are stylized, stretch the boundaries of realism, or are blatantly fantastic. Even though some of these elements are unrealistic, they still operate under mostly internally consistent in-universe rules so that readers can still make logical deductions about their use. While these rules are often explained over the course of cases, new readers who start in the middle may be unfamiliar with many of the tropes. This article lists those rules and discuses the degree of internal consistency within manga canon.

General tropes and style notes

• All manga Detective Conan cases are written so that the reader can solve the case. Solutions are mostly logical and relatively few contain errors or plotholes. Most cases (with the first cases being much more variable) are 3-6 chapters long, with the last chapter dedicated to the solution.
• Most clues in Detective Conan are shown close up, explicitly pointed out, or discussed, rather than hidden in the background of a panel. Most everything discussed in a case is relevant to the case itself or some overarching plot. Detective Conan's mystery presentation style is relatively generous in terms of helping a reader figure out what is important to a case, while still requiring a reader to figure out how all the details fit together.
• All the cases have solutions which will be uncovered. Unsolved cases are eventually solved; however, details of certain complex cases, (e.g. arc cases) may not always be explained in the main exposition of the solution.
• In arc mysteries, which are the 100-300 chapter mysteries typically involving a Black Organization member, clues are released so that the mystery becomes easier to solve towards the end of the arc. Clues towards the beginning are often better hidden and require more analysis to interpret correctly. More overt clues and bits of backstory that provide hints appear with increasing frequency nearer to the end of the arc.

Disguise

Disguise is a very commonly used plot device for cases in Detective Conan. The rules that govern disguise are a bit murky; they are most consistent within the context of a single character.

General Rules

• Adults can disguise as other adults within their personal limits. These personal limits vary by character.
• Adults cannot disguise as a whole child because of the blatant difference in height, although they may be able to disguise as part of a child, or just the voice.
• Actors, actresses, and magicians can be assumed to have some level of disguise ability unless it is stated otherwise.
• Differences in skin color can be hidden even on parts of the body which have to withstand wear such as the fingertips. This is apparently done without the use of latex.

Latex Masks

Main article: Disguise: Latex Masks

Latex masks are commonly used by advanced disguise practitioners to conceal their identity. There appears to be variation in the internal rules depending on which character is using them.

• Latex masks are only created by certain advanced actors or magicians. These include Kuroba Kaito, Kuroba Toichi, Vermouth, Kudo Yukiko, and Chikage Kuroba (Phantom Lady).
• Latex masks do not inhibit the facial expressions of characters, including blushing and sweatdrops..
• Latex masks can be detected by pinching the face. Keep in mind that not all disguises need masks.
• Latex masks are vulnerable to disruption, but the tolerance is unclear. Kaitou Kid stated that he could not put Jirokichi's motorcycle goggles on over his mask, but was able to put on a gas mask while disguising as Sonoko. Vermouth, Kid, and Conan have worn glasses and hats with a latex mask. Latex masks have also been shown to be resistant to some moisture, touching, and explosions.
• Latex masks can be stashed on the disguiser's body until needed without issue or disruption.
• Other types of disguise can be worn on top of a latex mask if they are removed gently.
• It is unclear if one latex mask can be worn on top of another and removed without disruption. This situation has never been definitely shown in Detective Conan manga canon, while it has in Magic Kaito.
• There is significant inconsistency about how long it takes to make a latex mask. Kaitou Kid could make a Shiho Miyano on the spot after Conan asked him to, while Yukiko is shown taking many hours to apply a single mask.

Character-specific Rules

Kuroba Kaito

• Kuroba Kaito can disguise as any teen or adult, but not the whole body of a child. Differences in adult height and weight don't seem to matter for Kaito. Kaitou Kid has disguised as Ran Mouri who is 14cm shorter than him and fooled Shinichi. He has also disguised as Kogoro Mouri who is significantly taller.
• Kuroba Kaito can imitate someone if he has seen a video of them.
• Kuroba's disguises are very accurate. He can do a woman's figure nearly perfectly and fool detectives who have known that woman for most of their life.
• Kuroba can get into disguise, including putting on a latex mask and full change of clothes, in a second or less.
• Kuroba can produce latex masks on the spot, and never seems to lack appropriate clothes or other accessories that are part of the disguise.
• As of 925 chapters, in cases where one of the goals is to figure out who Kaitou Kid is disguised as, the solution has never been the same twice. That is Kaitou Kid has never disguised as the same character for the majority of a case.

Vermouth

• It is unclear how long Vermouth needs to produce a mask or if she can apply one as fast as Kaitou Kid.
• Vermouth can imitate someone if she has observed them.
• Vermouth can make a mask of a person and find and buy closely matching clothes if she can observe the person with enough lead time.

Yukiko Kudo

• Yukiko seems to need time on the order of hours to make a latex mask.
• She has so far been limited in her disguise to adult women and her husband.

Crime Scene Investigation

Crime scene investigations and procedures are optimized so that interesting cases can easily develop and teenage detectives can easy enter the scene, search for clues, make logical deductions, and extract a criminal confession within several hours.

• Proper crime scene procedures like separating witnesses to prevent collusion, not announcing findings in front of suspects, removing suspects to prevent tampering, and photographing all the evidence before moving or touching it are generally ignored. Occasionally this can affect cases by (e.g. by allowing witnesses to tamper or collude) but the solution will inevitably be reached in the end. Any negative consequences from improper procedure are ignored and not taken into account for future cases.

• Not driving a culprit to suicide by cornering them when they still can act is the only major change to date that Shinichi has made in his investigative process due to previous negative consequences.

• Police are willing to allow detectives and anyone allied with a well-known detective to access crime scenes, especially if they have demonstrated their worth in a previous case. It's generally more notable when police don't allow detectives or their allies to examine a crime scene.
• Forensic results of all types usually come back during the same investigation. When they don't, it is often because it would make the case too simple, so the detective must find another way to solve the case with more primitive methods while waiting.
• Forensic results will never be wrong or inconclusive without some reason why.

Common clues

In order to simplify investigations and allow more complex and interesting murder mysteries, Aoyama Gosho has taken many liberties with murder-related devices and their corresponding clues. As a result, cases are very stylized, usually sacrificing some realism for reader convenience. Forensics has improved significantly since the beginning of Detective Conan, especially in ability to detect DNA. Cases are usually written with a concurrent level of forensics and technology.

Blood and bloodstains

• Blood and other liquids will form particular spatter patterns depending on the circumstances. Gunshot will produce fine small spatter, while drips from high up will make a splashed dot. Blood spatter patterns usually only matter to a case if they are shown up close and with some detail.
• Wiped blood, trace blood, and blood transferred by contact can be detected with luminol.
• Any handheld weapon (like a knife) that causes a puncture in a victim will almost always splash the weapon and murderer with blood.

Dying messages

• Dying messages are created by the victim before they lose consciousness, and real ones are not found in cases where a truly unaware victim was killed instantly.

• Scenarios similar to dying messages can be encountered in any case where the victim of a crime has a limited time leave a clue, such as a kidnapping or a battery.

• The most common type of dying message references the killer's name.

• If the married victim was killed by their spouse, the wedding ring is a classic dying message.

• Dying messages usually fall into one of three categories: Straightforward (with a twist so the case won't be too easy to solve), uniquely constructed with whatever materials are closely at hand, or cryptic out of fear the murderer will notice and erase it.

• Many straightforward-type dying messages are simply the victim's name, but it was changed or various circumstances have caused that name to come out unclearly.

• Fake dying messages created by the culprit are rarer than regular dying messages, but are not too uncommon.
• Solving the dying message is usually the central part of the case, but dying messages are rarely the only clue.
• Handwriting analysis can be performed on a sufficiently long handwritten dying message to see if it is genuine, as long as the victim has another writing sample it may be compared to.

Fingerprints

• Smudged, partial, or un-matchable fingerprints are almost never a problem. If a culprit touched something barehanded and did not wipe the prints off with a cloth, then they can be identified.
• Fingerprints can be obliterated by wiping them off with a cloth; however, fingerprints are never disrupted when a detective uses a handkerchief or the like to lift and hold an object.
• Applying gloves or glue to the fingertips prevents leaving fingerprints. Unlike gloves, glue isn't noticeable, but it makes the fingertips slippery.

Poison

Cyanide

The cyanide ion ( CN^- ) is the most common poison used for murder in Detective Conan. Here are the in-universe rules that it follows:

• Tiny doses of cyanide are lethal. A lethal dose can be transferred by contact (e.g. cyanide applied to a button pressed with one finger is enough to kill a victim if the victim licks that finger later.) Victims never seem to notice cyanide applied to the surface of an object. An even tinier dose of cyanide is lethal if it is introduced directly to the bloodstream via a needle or cut.
• Cyanide kills its victim within seconds if it is ingested. It apparently does not cause food or drink to taste unusual.
• The typical victim usually loudly screams moments after they have been poisoned and then collapses.
• A detective can tell if a victim died of cyanide ingestion by the smell of almonds from their mouth. (More details needed here: lip/face color, eye changes, etc.)
• Victims who have died of cyanide are often shown with a trail of foam or saliva from their mouth.
• Unless explicitly brought up as plot point in an investigation, it is assumed anyone can obtain cyanide.
• Traces of cyanide can be detected with a certain forensics chemical. This typically shows smears everywhere the cyanide was brought into contact with. These smears can be chemically erased with thiosulfate which itself can be detected with a solution of iodine.

(Check and see if this was used in manga canon* Extensive skin contact with cyanide without ingestion causes headaches and the feeling of being ill-at-ease)

Guns and gunshot

• Gunshots create a cloud of powder which sticks to the shooter's whole body head to toe unless they block it with an item like an umbrella. The powder residue can be detected forensically unless the person washes or changes their clothes.
• Fireworks and recordings of gunshots from a television program turned to high volume can trick detectives and police into thinking they heard an actual gunshot.
• Despite Japan having extremely strict regulations on guns and handguns in particular, it is assumed anyone can obtain a handgun, unless explicitly brought up as plot point in an investigation.
• Blank-firing guns can be used at point-blank range without leaving any sort of lasting burn or damage on the person it was fired at.

Strangulation, Suffocation, and Drowning

• Victims who were strangled usually have petechiae on their conjunctiva -burst blood vessels in the whites of their eyes.
• A victim that was strangled is shown with appropriate bruising on their neck. (e.g. A rough line ringing the neck is indicative of strangulation with a cord.) Bleeding caused by strangulation is shown as splotches around the line and indicates that blood was transferred to the murder weapon.
• Starting in Volume 66/Episode 575 (CHECK THIS!), scratch lines on the neck called "Yoshikawa Lines" are used to show that the victim was awake and clawed at their neck while being strangled.

• Drowning is indicated by fluid in the lungs, which may be analyzed to ascertain what sort of liquid the victim drowned in.
• Victims can drown in any amount of liquid that can cover their face, including small buckets.

Blunt force trauma

• The head is the most common target for blunt force-type attacks.
• Victims of head trauma may survive (often conveniently unable to give testimony until the case is resolved), die immediately, or die after having enough time to leave a dying message. It depends on the needs of the case. Whether a victim died immediately or lived for a while can be discovered with a police autopsy.
• Culprits may mistake a beaten but alive individual as dead in certain circumstances.
• Single lethal strikes to the head are relatively common, even for small female culprits killing healthy adult men. That said, multiple strike killings are not uncommon either.
• Lethal strikes to the head tend to be bloody affairs which splash blood on the weapon and the killer.

Time of death estimation

• By observing physical conditions, a detective can estimate how long it has been since a person died. Common time of death observations are the temperature of the body and the progression of rigor mortis

• Detectives and police in Detective Conan can often tell without any advanced equipment roughly when someone died by handling the body, if they died recently.
• Detectives, police, and medical personnel usually have the skills needed to perform a time of death estimation. Medical personnel in Detective Conan are generally capable of making additional analyses despite other specialties they may have.
• Police forensics are the most reliable at determining the time of death.

• The apparent time of death can be altered, even affecting professional estimations, if the body has been in abnormal temperatures. Warm temperatures speed up the progression of the time of death signs and make the death appear to have happened much earlier. Cooler temperatures make the death appear to have happened later.
• The time of death can be obscured by thorough burning of the body.
• Abnormal conditions such as being submerged can also affect the apparent time of death (this was an early case, the one where Ran was drowned in a sink I think?)
• Once the body has decomposed to the bone, the application of lime may (speed up decomposition Code of stars and tobacco) or slow down decomposition (Teitan murder with Rumi). (I need to work this out later.)

Murder methods and motives

Motive

Murders are almost never random (less than 5% for sure). Culprits almost always have a specific motive to target their victims. About the only time random victims are chosen is when the culprit needs to force a misinterpretation to throw the police and future victims off the trail (e.g. create an alibi, disguise the method, etc).

The three most common types of murder motives in multi-suspect murder cases are:

1. The victim(s) were involved in a past event and the culprit acts on a sense of vengeance. Not only is this setup common in regular single-victim cases, this is the most common formula for non-inheritance-based serial murders.
2. The victim(s) has some type of bad personality. This "asshole victim" victimized each of the suspects in various ways so they each have a plausible motive to kill. A much rarer variant that is similar in execution is a case where the victim is generally righteous and the suspects have bad personalities. This variant is more likely to show up in inheritance-based cases. Yet another version is the case where the culprit and the victim are all problematic (e.g. the culprit committed a crime, and the to-be victim found out and is blackmailing them).
3. The victim(s) are witnesses to a crime and must be eliminated. This is a less common pattern than the other two, but it more likely to arise in a serial murder.

Non-murder cases such as threats and kidnappings often have similar motive patterns, minus the killing of course.

• If a backstory that explains the motive is revealed in the investigation stage of the case, usually all the suspects will have been involved and have some plausible reason to kill.
• Misunderstandings by culprits are relatively common, thus making their actions tragic.
• The reason why a culprit motivated by a long past case chooses to act at the current time is often because a long running plan has reached a certain symbolic or required time to act, or the culprit uncovered new information that spurred an immediate emotional reaction.
• Murders may follow particular themes, especially serial murders. (e.g. Furinkazan, The Naniwa Serial Murder Case, Tottori Spider Mansion Demon) Sometimes the themes are part of the trick, or intended to mislead the the reader.

Locked room situation

Locked rooms are a classic mystery setup where the victim is killed in a sealed space, so superficially it appears as though the victim committed suicide or the crime is "impossible". Locked rooms can be actual locked rooms or similar situations where access is restricted and comings and goings are monitored.

• Solving the locked room trick is often the central part of the case.
• Most locked rooms are made to appear as suicides by the culprit. There is a rarer second type: "impossible crime" locked rooms where the victim could not have killed themselves yet it appears that no one else could have done so either.

There are a variety of tricks used to create locked rooms. Some that have been used in Detective Conan include:

• A trick to lock the room or seal the space from the outside. Several varieties of tape and string tricks have been shown over many cases.
• Sealing the space from the outside, and then using a trick to return the "key" to the locked room so that it appears to have been locked from the inside.
• The culprit pretends an unlocked locked room is locked. For instance, if the culprit is part of the group to initially discover the body, they may lie about the status of the locks or tamper with the crime scene to create a false impression the room was properly locked.
• The locked room is actually a red herring altogether, and the real relevant location was never a locked room to begin with.
• A secret point of ingress and egress, such as a secret passage or tampered window. This is quite rare.
• The culprit never leaves the room, but instead mixes in with the first discoverers and appears to have come from the outside. This is very rare.

Black Organization's involvement

• A crime whose scene has conspicuous errors is unlikely to have been perpetrated by the Black Organization, and such reasoning has been used by Conan and Haibara observe to rule out their involvement.
• The Black Organization is prone to having their investigations interrupted and their targets prematurely killed by unrelated cases, which is often how Conan finds out about their involvement.
• Black Organization agents are quick to kill their own members or allies if they severely err or become liabilities. Movie canon includes more instances of this. Agents may also commit suicide if they about to be captured.
• The Black Organization is prone to abort plans if circumstances change.
• Vermouth is especially unlikely to followup on intended victims who get away from her for various reasons.

APTX 4869 and its antidote

APTX 4869 is a fantastic drug that the Black Organization developed and caused Shinichi Kudo to shrink from high school age to first grader. Shiho Miyano made a prototype antidote that cancels out the de-aging effects of APTX 4869 for a short amount of time.

• APTX 4869 apparently cannot be detected with any toxicology test when used to murder someone, although it is unclear what cause of death a coroner would blame if examining an APTX 4869 victim. In the Haneda Kohji case, the cause of death was ruled to be unclear.
• Baijiu will cause the reversion of a de-aged person to their full adulthood at least once, but not a second time if more is drunk directly after. It takes a significant amount of time for the baijiu to begin working. Both times a reversion was shown, the person was ill with a cold that was then exacerbated by the reversion. It is unclear if being ill is required for baijiu to work.
• Most times a temporary antidote to APTX 4869 was taken, the person receiving it was ill with some sort of respiratory infection. However Shinichi has once used an antidote in good health and it worked as expected.
• The reversion both ways is extremely painful, but very fast. When a temporary antidote begins to wear off, it is signaled by shooting chest pain that becomes steadily more frequent and painful. How much and for how long a character is debilitated by the pain and whether or not they avoid screaming seems to mostly be determined by the needs of the author rather than a consistent rule.
• A temporary antidote works immediately.
• A second temporary antidote can be given before the first one wears off to extend the duration without de-aging in between. Taking a second temporary antidote after the first causes it to last for a much shorter amount of time, usually how ever long it takes to resolve a case.

Gadgets

Stun gun wristwatch

• As long as the dart hit a person in their exposed skin, they will fall asleep within seconds, although in some case (for example, Gin), shooting themselves at the place being hit can help them stay awake.
• A person being hit with a dart falls asleep for some period of time; however, if being physically hit (on the head), they will wake up sooner than the effective range of the dart.
• Being hit with a dart leaves no mark on a person's skin.
• Most people experience some memory lapse when being asleep, and cannot recall events during that time. Afterward, they could not recall why they fall asleep, and attribute their lack of knowledge in intermediate events for some strange phenomenon. Kogoro Mouri; however, does suspect some time upon being hit multiple times, but dismisses his strange feelings anyway.

Criminal Tracking Glasses

• Its range is up to 20 km, and it can be so accurate that it pinpoints exactly where a person is. For example, Ai Haibara used the glasses once to locate Conan who passed out inside a locker in a building. In current technology, GPS devices only have accuracy up to 10 meters, and work poorly in indoor environments.

Power-Enhancing Kick Shoes

• The kick from its strength is so strong that it can smash a wooden door just by using a regular soccer ball.
• The recipient get knocked out almost instantly after being hit, unless having sufficient armor (such as thick coats or helmets).

Human physiology

• Characters in DC are overwhelmingly right-handed, far more than the usual ~90% of the population. Lefthandedness usually turns out to be a plot point when present (as a clue, or to differentiate suspects.)
• Handedness can be determined by looking at a character's actions. Using guns, handwriting, and miscellaneous actions such as gesturing, touching the face, manipulating objects are the most indicative. Phone use and door opening are among the least indicative. Characters are almost never ambidextrous.
• Mendelian law of inheritance applies and can be used as evidence, but it is unclear if Gosho consistently applies these rules when they are not relevant to a case solution.

"Superpowers"

Certain characters have special abilities that are best described as slightly supernatural. None of these "powers" have been scientifically verified to exist in real life.

Shinichi's stare sensor and other psychic powers

• Shinichi has the ability to tell when he is being watched, especially with malevolent intent. This sense applies especially to Kaitou Kid and criminals with bad intentions.

• Shinichi can get bad feelings when cases are not completely resolved, although they appear to be superficially over. Some of these moments are "realistic" where Shinichi is reacting to evidence or events that have not been explained, but in other examples Shinichi seems to tap into some sort of "detective's intuition".

• Shinichi seems to have a slight psychic link with Ran. He can sort of sense when she is in danger, although not as strongly as she can sense his moments in trouble. In one case where a bomb was planted at Teitan High, Ran began to feel uneasy as if Conan had managed to send her his distress psychically.

Ran's Intuition

• Ran can recognize people in disguise, relatives of other characters, or those who have changed appearance dramatically, even if she has not been around them long before. Her intuition has never been completely incorrect or uncalled for.

• Ran can also sense when Shinichi is in danger at a distance, which causes her to feel uneasy and often seek him (or Conan). In one case where a bomb was planted at Teitan High, it was almost like Conan had managed to send her his distress psychically.

• Ran always seems to win at games of chance or gambling beyond what is probable. This power of hers is acknowledged in-universe by her father and Shinichi.

Shiho's Black Organization sense

• Shiho has the ability to sense when Black Organization members are around, which she characterizes as their unique "smell" or "pressure". So far, her sense only detects Black Organization members and not people with malevolent intent generally, however, it doesn't always trigger when Black Organization members are present. nor does it reveal their numbers. Sometimes the sense is fleeting (Okiya, or Akai passing by pursuing James Black), or context sensitive (when Akemi was planning the bank robbery).

Floating Timeline

A floating timeline is a literary device used in many long running comics to explain why characters do not age with the passing of real-world time. It occurs where there is a mismatch between the apparent progression of time according to the reader and the canon progression of time which is how much time the characters say has passed since a certain event. In Detective Conan, it is canonical that less than one year has passed since Shinichi shrunk. Meanwhile, according to the reader, the apparent rate of time progression matches the real world publishing schedule of the chapters in the Shonen Sunday magazine. This is not a mistake, but a deliberate choice by Gosho to give himself flexibility, variety in crime settings, and allow his comic to keep up with modern developments so that it can stay relevant and not appear old-fashioned.

Because the real world timeline and the Detective Conan timeline are inherently contradictory, it is absolutely useless to attempt to figure out when specific events happened relative to each other. There is no logical solution to explain how two decades-worth of season changes, technological progress, holidays, summer breaks, etc, can fit into less than a year's worth of time. To fit all the cases in one year, Conan must be solving about one case a day with no time for school or any other activity. Attempting to reorder cases or ignore certain ones simply creates even greater violations of causality. The only solution is to not think about it too much. Ultimately the floating timeline doesn't matter to the major overarching mysteries.

That said, real world events can impact individual cases when they serve as clues in those mysteries. Seasons and holidays in the manga match the real world publishing schedule of the chapters in the Shounen Sunday magazine. The technology and forensics techniques also follow along with the real world. Therefore each individual case must be approached with the corresponding real world time in mind.