Rules of the Death Note

Within the fictional universe of the manga and anime series Death Note, a Death Note is a notebook held by a Shinigami ("death god") which has the power to kill people simply by writing their names in it. All Death Notes follow a long set of specific rules, which, while not explicitly noted within the Death Notes themselves, are revealed through the course of the individual manga volumes and, in the case of the anime, via eyecatches.

Written rules
Before the series begins, Ryuk writes instructions in English inside his Death Note with the belief that English is the most popular language in the human world.
 * The human whose name is written in this note shall die.
 * This note will not take effect unless the writer has the person's face in their mind when writing his/her name. Therefore, people sharing the same name will not be affected.
 * If the cause of death is written within 40 seconds of writing the person's name, it will happen.
 * If the cause of death is not specified, the person will simply die of a Heart attack.
 * After writing the cause of death, the details of the death should be written in the next 6 minutes and 40 seconds (400 seconds or approx. 6.66 minutes).
 * The Death note will not affect those under 780 days old.
 * A death note will be rendered useless if the victim's name is misspelled four times.
 * If a death note is lost or stolen the owner will lose ownership unless it is retrieved within 490 days.

Fake rules
These rules were written in the Death Note to aid Light in a scheme he came up with to clear his and Misa's names. They were written by Ryuk but are completely false.
 * If the owner of a Death Note does not use the notebook after 13 days time, he or she will die.
 * If the Death Note is burned, torn up, or otherwise rendered useless, any people who have touched the Death Note will die.

Light uses the first rule to convince the investigation team that because the killings had stopped for two weeks while he was imprisoned, he could not possibly be Kira. Light uses the second rule to prevent the team from destroying the Death Note.

Other rules
Though the main rules cover the Death Note's basic function, several secondary rules govern how the Death Note operates in conjunction with other Death Notes or how it can be used. Throughout the series, other rules are revealed, one of the most prominent being, "When the same name is written on more than one Death Note, the Note which was first filled in will take effect, regardless of the time of death." This rule played an important role in the movie, as L used it to prevent Kira from killing him. A few of them match the rules Ryuk wrote inside the Death Note, but most of them are rules that are not known by humans and, in some cases, even the Shinigami. These rules are revealed at the end of certain chapters in the volume format of Death Note and the beginning of the Jump format chapters, on black pages that contain only the rules.

Other minor rules determine how and to what limits a Death Note can be used. For example, while a victim whose name is written in the Death Note is more or less compelled to follow whatever instructions the writer gives for the cause of death, it cannot force a person to do something they would be physically or mentally incapable of doing; for example, while the user of a Death Note could force their victim to fly halfway across the world and commit suicide, they could not do the same within an unreasonable time frame, such as a single hour. In such cases, the Death Note defaults to a heart attack. Any type of substance can be used to write names in the Death Note so long as the writing is permanent; Light pricks his finger and uses his own blood to write Higuchi's name in the Death Note piece hidden in his watch, to kill him without arousing suspicion.

In the eyecatches of the last chapter/episode (then, the two last eyecatches of the series), the "rules" revealed are not Death Note rules, but the rules of life itself, as it says:
 * All humans will, without exception, eventually die.
 * If a human uses the Death Note, he/she can neither go to heaven nor hell
 * Once dead they can never come back to life.

Each rule is central to the chapter/episode, as it reminds that even Light, a self-proclaimed "god," will die one day as all humans do.

Secondary Rules
These rules are explained in between eyecatches of episodes and in the manga.
 * This note shall become the property of the human world, once it touches the ground of (arrives in) the human world.


 * If anybody brings up a topic, he or she must tell the other person.


 * The individual who brings up a topic must tell the other person if that person wants to know or if he or she asks to know.


 * If a human uses the note, a Shinigami usually appears in front of him or her within 39 days after he/she uses the note.


 * Shinigami, the original owners of the DEATH NOTE, does not do, in principle, anything which will help or prevent the deaths in the note.


 * A Shinigami has no obligation to completely explain how to use the note or rules which will apply to the human who owns it.


 * A Shinigami can extend his life by putting human names on the note, but humans cannot.


 * A person can shorten his or her own life by using the note.


 * The human who becomes the owner of the DEATH NOTE can, in exchange of half of his or her remaining life, get the eyeballs of Shinigami which will enable him or her to see a human's name and remaining lifetime when looking through them.


 * A Shinigami cannot be killed even if stabbed in his heart with a knife or shot in the head with a gun. However, there are ways to kill a Shinigami, which are not generally known to Shinigami.


 * The conditions for death will not be realized unless it is physically possible for that human or it is reasonably assumed to be carried out by that human.


 * The specific scope of the condition for death is not known to Shinigami, either. So, you must examine and find out.


 * One page taken from the DEATH NOTE, or even a fragment of the page, contains the full effects of the note.


 * The instrument to write with can be anything, (e.g. cosmetics, blood, etc) as long as it can write directly onto the note and remains as legible letters.


 * Even the original owners of the DEATH NOTE, Shinigami, do not know much about the note.


 * You may also write the cause and/or details of death prior to filling in the name of the individual. Be sure to insert the name in front of the written cause of death. You have about 19 days (according to the human calendar) in order to fill in a name.


 * Even if you do not actually possess the DEATH NOTE, the effect will be the same if you can recognize the person and his or her name to place in the blank.


 * The DEATH NOTE will not affect those under 780 days old.


 * The DEATH NOTE will be rendered useless if the victim's name is misspelled four times.


 * Suicide is a valid cause of death. Virtually all human beings have the ability to commit suicide. It is, therefore, not something "unbelievable to think of."


 * Whether the cause of the individual's death is either a suicide or accident, if the death leads to the death of more than the intended, the person will simply die of a heart attack. This is to ensure that other lives are not influenced.


 * Even after the individual's name, the time of death, and death condition on the DEATH NOTE were filled out, the time and condition of death can be altered as many times as you want, as long as it is changed within 6 minutes and 40 seconds from the time it was filled in. But, of course, this is only possible before the victim dies.


 * Whenever you want to change anything written on the DEATH NOTE within 6 minutes and 40 seconds after you wrote, you must first rule out the characters you want to erase with two straight lines.


 * As you see above, the time and condition of death can be changed, but once the victim's name has been written, the individual's death can never be avoided.


 * If you lose the DEATH NOTE or have it stolen, you will lose its ownership unless you retrieve it within 490 days.


 * If you have traded the eye power of a Shinigami, you will lose the eye power as well as the memory of the DEATH NOTE, once you lose its ownership. At the same time, the remaining half of your life will not be restored.


 * You may lend the DEATH NOTE to another person while maintaining its ownership. Subletting it to yet another person is possible, too.


 * The borrower of the DEATH NOTE will not be followed by a Shinigami. Shinigami always remains with the owner of the DEATH NOTE. Also, the borrower cannot trade the eyesight of Shinigami.


 * When the owner of the DEATH NOTE dies while the Note is being lent, its ownership will be transferred to the person who is holding it at that time.


 * If the DEATH NOTE is stolen and the owner is killed by the thief, its ownership will automatically be transferred to the thief.


 * When the same name is written on more than two DEATH NOTES, the Note which was first filled in will take effect; regard less of the time of death.


 * If writing the same name on more than two DEATH NOTES is completed within a 0.06-second difference, it is regarded as simultaneous; the DEATH NOTE will not take effect and the individual written will not die.


 * Shinigami must at least own one DEATH NOTE. That DEATH NOTE must never be lent to or written on by a human.


 * Exchanging and writing on the DEATH NOTE between Shinigami is no problem.


 * If Shinigami decides to use the DEATH NOTE to kill the assassin of an individual he favors, the individual's life will be extended, but Shinigami will die.


 * The dead Shinigami will disappear, but the DEATH NOTE will remain. The ownership of this DEATH NOTE is usually carried over to the next Shinigami that touches it, but it is common sense that it is returned to the Great Shinigami.


 * Only by touching each other's DEATH NOTE can human individuals who own the DEATH NOTE in the human world recognize the appearance or voice of each other's Shinigami.


 * An individual with the eye power of a Shinigami can see the name and life span of other humans by looking at that person's face. By possessing the DEATH NOTE, an individual gains the ability to kill and stops being a victim. From this point, a person with the DEATH NOTE cannot see the life span of other DEATH NOTE owners, including him or her. But, it is not really necessary for the individual to view the life span of neither him or herself nor other DEATH NOTE owners.


 * Shinigami must not tell humans the names or life spans of individuals he sees. This is to avoid confusion in the human world.


 * It is prerequisite for the DEATH NOTE used in the human world that a living Shinigami makes sure that the humans in the human world use it.


 * It is very difficult to consider that a Shinigami who has possessed a human could die, but if he should die, the DEATH NOTE that he brought into the human world will not lose its power.


 * In order to see the names and life spans of humans by using the eye power of Shinigami, the owner must look at more than half of that person's face. When looking from top to bottom, he must look at least from the head to the nose. If he looks at only the eyes and under, he will not be able to see the person's name and life span. Also, even though some parts of the face, for example the eyes, nose or mouth are hidden, if he can basically see the whole face, he will be able to see the person's name and life span. It is still not clear how much exposure is needed to tell the name and life span, and these needs to be verified.


 * If above conditions are met, names and life spans can be seen through photos and pictures, no matter how old they are. But this is sometimes influenced by the vividness and size. Also, names and life spans cannot be seen by face drawings, however realistic they may be.


 * Those with the eye power of Shinigami will have the eyesight of over 3.6 in the human measurement, regardless of their original eyesight.


 * The individuals who lose the ownership of the DEATH NOTE will also lose their memory of the usage of the DEATH NOTE. This does not mean that he will lose all the memory from the day he owned it to the day he loses possession, but means he will only lose the memory involving the DEATH NOTE.


 * Whenever an individual with ownership of more than two DEATH NOTES loses possession to one of the DEATH NOTES, he will not be able to recognize that DEATH NOTE's Shinigami's appearance or voice anymore. Shinigami himself will leave, but all the memory involving that DEATH NOTE will remain as long as he maintains ownership of at least one other DEATH NOTE.

- When Shinigami's DEATH NOTE is handed to a human. - Essentially, finding a human to pass on the DEATH NOTE should be done from the world of Shinigami, but if it is within 82 hours this may also be done in the human world. - When a Shinigami stalks an individual with an intention to kill them, as long as it is within 82 hours of haunting them, Shinigami may stay in the human world.
 * Shinigami must not stay in the human world without a particular reason. Conditions to stay in the human world are as follows:


 * Shinigami must not hand the DEATH NOTE directly to a child under 6 years of age (based on the human calendar).


 * The DEATH NOTE must not be handed to a child under 6 years of age, but DEATH NOTES that have been dropped into the human world, and are part of the human world, can be used upon humans of any age with the same effect.


 * If you just write, "die of accident" for the cause of death, the victim will die from a natural accident after 6 minutes and 40 seconds from the time of writing it.


 * Even though only one name is written on the DEATH NOTE, if it influences and causes other humans that are not written on it to die, the victim's cause of death will be a heart attack.


 * If you write, "die of disease" with a specific disease's name and the person's time of death, there must be a sufficient amount of time for the disease to progress. If the set time is too tight, the victim will die of a heart attack after 6 minutes and 40 seconds after completing the DEATH NOTE.


 * If you write, "die of disease" for the cause of death, but only write a specific time of death without the actual name of disease, the human will die from an adequate disease. But the DEATH NOTE can only operate within 23 days (in the human calendar). This is called the 23-day rule.


 * If you write, "die of disease" like before with a specific disease's name, but without a specific time, if it takes more than 24 days for the human to die, the 23-day rule will not take effect and the human will die at an adequate time depending on the disease.


 * When rewriting the cause and/or details of death it must be done within 6 minutes and 40 seconds. You cannot change the victim's time of death, however soon it may be.


 * You cannot kill humans at the age of 124 and over with the DEATH NOTE.


 * You cannot kill humans with less than 12 minutes of life left (in human calculations).


 * If you have traded the eye power of a Shinigami, you will see a person's primary life span in the human world.


 * The names you see with the eye power of a Shinigami are the names needed to kill that person. You will be able to see the names even if that person isn't registered in the family registration.


 * The number of pages of the DEATH NOTE will never run out.


 * If someone possesses more than one DEATH NOTE, by visualizing the victim, then writing down the name in one of the DEATH NOTES and the cause of death in the other, it will take effect. The order however, is unimportant, if you write down the cause of death in one DEATH NOTE and afterwards, write the name in the other, it will still take effect.


 * This can also be accomplished by two DEATH NOTE owners working together. In this case, it's necessary that the two touch each other's DEATH NOTES.


 * If a person loses possession of a DEATH NOTE, they will not recognize Shinigami by sight or voice any more. If however, the owner lets someone else touch his DEATH NOTE, from that time on, that person will recognize Shinigami.


 * In accordance with the above, the human who touched the DEATH NOTE and began to recognize Shinigami's sight and voice, will continue to recognize it until that human actually owns the DEATH NOTE and subsequently loses possession of it.


 * The owner of the DEATH NOTE cannot be killed by a Shinigami who is living in the world of Shinigami.


 * Also, a Shinigami who comes to the human world, in the objective to kill the owner of the DEATH NOTE, will not be able to do so.


 * Only a Shinigami that has passed on their DEATH NOTE to a human is able to kill the owner of the DEATH NOTE.


 * If a DEATH NOTE owner accidentally misspells a name four times, that person will be free from being killed by the DEATH NOTE. However, if the owner intentionally misspells the name four times, the DEATH NOTE owner will die.


 * The person whose name was misspelled four times on purpose will not be free of death by a DEATH NOTE.


 * There are male and female Shinigami, but it is neither permitted, nor possible for them to have sexual relations with humans. Shinigami also cannot have sex with each other.

Shinigami and Death Notes
A Shinigami must own at least one Death Note. That Death Note may also be used and owned by a human, but only if the Death Note falls to Earth and is found by a human. The Shinigami have to keep using the Death Note to kill people in order to extend their own lives.

A pact exists between the first human owner and the Shinigami who gave that person the Death Note. The pact is such that at the end of the owner's life, the Shinigami has to write down the owner's name in his own note.

How to kill a Shinigami
Rem is one of the few Death gods to discover how to kill a Shinigami. If a Shinigami uses the Death Note to extend the life of a human being it cares about, it will die since it will have failed in its eternal mission of shortening human lives. This was stated by Rem when she claims she would kill L for Light; she initially states that it would make no difference as it was to protect Light, whom she did not particularly care for. However, since she then had such an attachment to Misa (whom she was convinced would inevitably die if L was allowed to live and suspect her as Kira), she would die. Rem reveals this to Misa, who later reveals it to Light and Ryuk.

A Shinigami could end up killing itself as well, if it neglects to continue filling its Note with the names of humans. If it fails to do this then it will cease to lengthen its lifespan, and eventually run out completely.

A Shinigami may be killed by execution as well, in the Shinigami Realm. If a Shinigami breaks the laws of the Shinigami Realm, it is subject to one of nine levels of punishment, starting with level eight at the lowest infraction, going up to level one, and then the "Extreme" level. If a Shinigami is subjected to levels three or above, it will die after it is finished being punished. This is why Sidoh stops himself from telling Mello where the other Death Note is, after reading this rule in the scrolls he was given for his mission to retrieve his own Death Note, as he would be punished with "second degree" punishment and die.