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 blatantly fantastic or stretch the boundaries of realism. Even though 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.
• The vast majority of murder motives are usually personal (e.g. a grudge) or to silence a witness. That said, there have been isolated incidences of accidents, would-be-spree murderers, and attempted professional assassination.
• No recurring character, that is one who has appeared in person alive for more than one case, has been killed as of chapter 925. Any recurring characters who have died did so in their first case and reappeared in flashblacks, were stated to be dead from the outset, or faked their death.

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 was 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.

Murder-related plot devices

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.

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

• 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 struggled while being strangled.

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 unclear what cause of death a coroner would blame if examining an APTX 4869 victim.
• 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.

Forensics and Investigation

• 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.