Future Diary (term)

A Future Diary is the namesake device of the Future Diary series. Developed for the participants of the battle royale set by Deus Ex Machina, it is a communication tool (usually a cell phone) that can predict the future in a way that reflects its user.

Future Diaries appear in almost all Future Diary works, including the Future Diary -Another:World- series.

Overview & Background
The Future Diaries were the joint creation of two people: Deus ex Machina, who sought a means to find a successor to his throne as the God of Time and Space, and John Bacchus, who wished to further human evolution. With the former God's supernatural powers and the latter's vast resources and technical knowledge, they developed the first Future Diaries, representing different means to see the future and track others of their kind. Deus and John would continue to refine the concept and incorporate them into Deus's search for a worthy successor, eventually developing twelve unique Diaries that are given to the participants of Deus's Survival Game.

Future Diaries can take on a variety of forms, but all manifest as an object that can be used to record information about one's surroundings and opinions. The most common form is a cell phone, but some Diaries appear as computers, audio recorders, scrolls, and even coloring books. They present their user with predictions of the future seemingly written/recorded as if the user themselves had made the entries; each Diary has a different scope, which gives it certain advantages and limitations compared to the rest.

While each Future Diary has a different means of seeing the future, they always reflect their user in some way; their personality, occupation, hobbies, and general outlook. Some Future Diaries also have secondary abilities, such as Twelfth's ability to hypnotize people or Eighth's ability to grant Apprentice Diaries to others.

A person granted a Future Diary is called a Diary Holder. There are initially twelve Diary Holders, all candidates for Deus Ex Machina's Survival Game (Thirteen in the video game, The 13th Diary Holder); however, it is possible to create new Diary Holders by making Apprentice Diaries with the Eighth's Blog Diary. Interestingly, a Diary Holder is not necessarily a single person; for example, the Seventh candidate was actually two people with complementary Future Diaries. Additionally, it is possible to temporarily transfer ownership of a Future Diary to another person, allowing them to use their diary; similarly, stealing another Diary Holder's diary enables the thief to make use of its predictions.

Common Elements
Despite the differences between the diaries, there are certain common elements between them. First of all, the futures they present are not immutable; their users can act on the information presented by their Diaries to defy or avert a predicted event, thereby changing the entries on their Diary to match the new reality. If a user's future is altered by another person's actions, their Future Diary will automatically adjust its predictions as needed; if observed directly, the affected entries will appear or disappear in a manner befitting their medium. For instance, a cellphone-based Diary would have static cover the screen as the entries change, while the written medium Diaries have entries appear to fade away and reappear like drying ink.

The Future Diaries can also present special alerts to their users if a particularly significant event is predicted. Future Diaries are inextricably linked to their user's existence, meaning that a Diary Holder must protect their diary at all costs. If a Future Diary is destroyed, its Holder's body collapses into a singularity and fades from existence. Conversely, a Future Diary loses its powers if its holder is killed, lasting just long enough to present their Dead End before reverting to an ordinary object.
 * The most common and important of these alerts is the Dead End; an entry detailing the user's own demise. If this message appears, the user is doomed to die unless they can change the future to avert the Dead End; depending on the situation, the chances of successfully doing so can vary drastically, although it is usually very difficult. Some Future Diaries are more detailed than others when presenting a Dead End, giving warnings about the exact time and means of their user's death.
 * Another type of diary alert known to appear (albeit only shown in one diary) is the Happy End, a prediction that its user will succeed in their goals. Like the Dead End, it can be erased if the future changes in a way that threatens the user's goals.

List of Future Diaries
These Future Diaries are used by the participants of Deus's Survival Game.
 * The Indiscriminate Diary (無差別日記, Musabetsu Nikki?) : The diary used by the series protagonist Yukiteru Amano, also known as the First. It is a cellphone that gives him the ability to read the details of his surroundings, be it present or future. While this allows it to be very useful in most scenarios, it will not tell him anything about himself, which leaves him open to certain attacks. Additionally, the diary's predictions are based on Yukiteru's own perception of truth, preventing him from identifying deceit. It reflects his personality as a reclusive bystander.


 * The Yukiteru Diary  (雪輝日記, Yukiteru Nikki?) : Is the diary used by the Second, the series deuteragonist Yuno Gasai. It is a cellphone with entries detailing Yukiteru's actions in ten-minute intervals. While it is one of the weaker Future Diaries in terms of scope, it makes a fearsome combination with the Indiscriminate Diary; Yuno can predict what happens to Yukiteru, and Yukiteru can predict everything else. This diary reflects Yuno's obsessive love for Yukiteru.


 * The Murder Diary  (殺人日記, Satsujin Nikki?) : The diary used by the Third, Takao Hiyama. It is a cellphone that identifies people he wishes to kill and tells him where they are at any given time. However, it does not tell him what his victims will do, leaving him vulnerable if they decide to defend themselves against him. It reflects his nature as a psychotic serial killer. It also makes the user invulnerable to bullets and bombs alike, this was shown when the owner confronted the user of the Escape Diary.


 * The Criminal Investigation Diary (捜査日記, Sōsa Nikki?): The diary used by the Fourth, Keigo Kurusu. It is a cellphone that predicts the results of his investigations into criminal activities, reflecting his position as the chief of police in Sakurami City and his desire to protect the innocent from lawbreakers . While this is useful for tracking most of the other Survival Game candidates, it still requires that Kurusu dedicate time and resources to maximize the benefits of his diary's predictions.


 * The Hyper Vision Diary (はいぱーびじょんだいありー, Haipā Bijon Daiarī?) : The diary used by the Fifth, Reisuke Houjou. It is a coloring book that predicts three entries per day, one in the morning, noon and night. While it may seem weak, it allows Reisuke to plan out his entire day at once; it also provides simple pictures to further clarify each prediction. His diary may reflect his rather impatient and childish behavior.


 * The Clairvoyance Diary (千里眼日記, Senrigan Nikki?): The diary used by the Sixth, Tsubaki Kasugano. It is a large scroll which shows entries of what her subordinates see, allowing her to strategically direct them and gather information over a large area. However, its reliance on her followers leaves Tsubaki open to sabotage and misdirection, and its large, fragile nature makes it extremely vulnerable to use. It reflects her position as the figurehead of the Omekata religion, her poor eyesight, and her supposed clairvoyant powers.


 * The Exchange Diaries (交換日記, Kōkan Nikki?): The diary used by the joint Sevenths, Marco Ikusaba and Ai Mikami. It is a pair of cellphones that each describe the other holder's future, allowing them to coordinate their efforts and track each other even if they are apart; alternately, they can switch phones and read their own futures. As a dual Future Diary, it is at its weakest when its users are separated; however, losing one does not disable/kill the other. It reflects the deep bond of love between Marco and Ai.


 * The Blog Diary (増殖日記, Zōshoku Nikki?, "Propagation Diary") : Also translated as the Server Diary, this laptop computer is the diary used by the Eighth, Kamado Ueshita, Unlike most of the other Future Diaries, it cannot predict the future; instead, it enables Kamado to transform people who link to the Blog Diary into Apprentice Diary Users (see below), giving her a potential army to fight on her behalf. It reflects her loving nature and her job as the director of the Mother's Village orphanage.


 * The Escape Diary (逃亡日記<span class="t_nihongo_comma" style="display: none;">, Tōbō Nikki<span class="t_nihongo_icon" style="color: rgb(0, 0, 238); font: bold 80% sans-serif; text-decoration: none; padding: 0pt 0.1em;">?) : The diary used by the Ninth, Minene Uryu, a cellphone whose entries inform her on how to escape from dangerous situations. It provides specific details about the escape routes (where to go, how long to hide, etc.), but it lacks offensive utility; furthermore, it can still display a Dead End flag if Minene is completely cornered. It reflects her nature as a survivalist since a young age.


 * The Breeder Diary (飼育日記<span class="t_nihongo_comma" style="display: none;">, Shiiku Nikki<span class="t_nihongo_icon" style="color: rgb(0, 0, 238); font: bold 80% sans-serif; text-decoration: none; padding: 0pt 0.1em;">?) : The cellphone diary used by the Tenth, Karyuudo Tsukishima, who also loaned it to his daughter, Hinata Hino. It enables its user to control Karyuudo's dogs and see their futures, allowing the user to efficiently track their enemies and attack from multiple angles at once. While it requires greater levels of concentration as more dogs are used, this weakness can be circumvented by commanding dogs in groups or by using a computer to manage their locations. It reflects Karyuudo's great love for dogs.


 * The Watcher (ザウォッチャ Za Uotcha): The diary used by the Eleventh, John Bacchus, is a tablet that can read the entries of every other diary at will (including Apprentice Diaries) and reveal their Holders' locations. This enables John to know exactly what will his enemies do and how to defend himself from them or catch them off-guard, making it one of the strongest Future Diaries of all. However, since it only reads other entries without confirming their validity, it is vulnerable to misinformation; additionally, it lacks any ability to predict the future on its own, not even providing a Dead End flag. It reflects John's megalomania, his dream to "evolve humanity", his job as the mayor of Sakurami City, and his role as the co-creator of the Future Diaries.


 * The Justice Diary (正義日記<span class="t_nihongo_comma" style="display: none;">, Seigi Nikki<span class="t_nihongo_icon" style="color: rgb(0, 0, 238); font: bold 80% sans-serif; text-decoration: none; padding: 0pt 0.1em;">?): The diary used by the Twelfth, Yomotsu Hirasaka, an audio recorder which predicts and alerts him to acts of "injustice" around him; unfortunately, it doesn't discriminate between great acts and simple acts such as littering. It also has the ability to hypnotize people, putting them under his complete control. It reflects him as the heroic vigilante he claims to be and his desire to spread "justice" across the world.


 * The Video Diary: (Game Only) The diary used by the Thirteenth, Azami Kirisaki, a digital video camera that allows her to visually record the future and shows her what she will record on her diary.

Apprentice Diaries
Apprentice Diaries are a unique sub-set of Future Diaries provided to people who link themselves to the server used by the Eighth's Blog Diary. Apprentice Diary Holders are introduced midway through the game when the Seventh and the Eighth make their move, as most of the Apprentices seen are in fact orphans under the care of Kamado Ueshita. After the appearance of these Holders, Deus himself tried to clarify some points regarding them and the game. Although he never clearly states anything about them, some traits are known and others are hinted at:


 * As with all Future Diaries, the abilities of Apprentice Diaries reflect their Holders in some way.
 * All Apprentice Diaries take the form of cellphones, although


 * Apprentice Diaries can be given to active participants in the Survival Game if they connect to the Blog Diary (e.g. the Sevenths).
 * It is heavily implied that an Apprentice Diary User is ineligible to become God, presumably because they were not chosen by Deus as potential successors. None of the Apprentice users express a serious desire to try, so whether or not they would be able to win the Survival Game is unclear.
 * Destroying an Apprentice Diary does not kill the user, possibly because they are not considered to be a candidate to succeed Deus.
 * The Apprentice Diaries can only function if they are connected to the Blog Diary's server; if the connection is interrupted, they lose their power (however, they immediately regain their functionality once the connection is restored). This appears to be a weakness specific to them, as the Seventh and Eleventh's Future Diaries show no such vulnerability. As an extension of this, all Apprentice Diaries would presumably be lost forever if Kamado (the user of the Blog Diary) dies.
 * Apprentice Diary users can join with whatever party they see fit, not necessarily the Eighth's.


 * Although it never comes up in the series, it is suggested that an Apprentice Diary cannot be taken back once it is granted to a user.

The following is a list of the known Apprentice Diaries and their users if known:


 * The Flirting Diary: Used by Ai Mikami. It allows her to see which men she's going to flirt with; mostly used to track targets. It may represent her awareness of her own attractiveness and her willingness to use it to her advantage in the Survival Game.


 * The Brawler Diary: Used by Marco Ikusaba. It allows him to predict his opponents' moves in combat, giving him a chance to counter or dodge as necessary. It represents his combative nature and desire to meet his foes head-on.


 * The Orphan Diary: Used by Orin Miyashiro. Its abilities are unknown, but it is suggested that it predicts the future of Ueshita's orphans.


 * The Copy Diary: Used by Ta-kun. By making a connection with a diary, it is capable of copying its abilities, including normal Future Diaries.


 * The Kosaka King Diary: Used by Ouji Kosaka. It predicts his successful moments, mostly used to reverse a situation. It does not tell him of his failures; therefore, he can fail if he relies too much on his successes. It represents his arrogant surety in his own superiority.
 * The Neo Kosaka King Diary: A replacement and upgrade of the previous Diary, used by Ouji Kosaka. This one predicts the successes of Kosaka and his friends; it's suggested that it retains the same weakness as the previous one. It represents his belief in his friends as well as himself.


 * The Friendship Diary: Used by Hinata Hino. It predicts conversations she will have with her friends, allowing her to track their conditions. It represents her outgoing nature and desire to keep in touch with those close to her.


 * The Hinata Love Diary: Used by Mao Nonosaka. It predicts everything related to Hinata, working in a similar way to Yuno's Yukiteru Diary. It represents Mao's attraction to Hinata.


 * The Secretary Diary: Used by Ryuji Kurosaki, John Bacchus' secretary. It records and predicts John's actions, serving as a countermeasure for the Watcher Diary's weakness to misinformation. It likely represents Ryuji's loyalty to John or his role as his secretary.


 * The Detective Diary: Used by Aru Akise. It can read the entries of the Diary Users and predict their future, regardless of any changes that may be made. It represents his desire

Several unnamed Apprentice Diaries are seen being granted to the citizens of Sakurami City after John Bacchus connects the city's phones to Kamado Ueshita's diary and the HOLON III supercomputer - including a terminally ill man's diary telling him he will die soon, a stock manager discovering the next day's prices, and a young boy's diary telling him what food his mother will cook for dinner.

Scrapped Future Diary Prototypes
At one point, Deus reveals that before the game was hosted, he and John created several prototypes of the Future Diaries. Although they were never used for the Survival Game, being refined into the Future Diaries seen in the series proper, they have been named and detailed:
 * The Radar: A Future Diary that predicts one's surroundings. Was likely refined into Yukiteru's Random Diary.
 * The Searcher: A Future Diary that predicts specific people's actions. Was likely refined into Yuno's Yukiteru Diary and possibly the Seventh's Exchange Diary.
 * The Supplier: A Future Diary that can provide others with Diaries. Was likely refined into Kamado's Blog Diary.
 * The Organizer: A Future Diary that gives details about an organization or group of people. Was likely refined into Tsubaki's Clairvoyance Diary and/or Karyuudo's Breeder Diary.
 * The Watcher: A Future Diary that can see the entries of other diaries. It was the only prototype that was not scrapped; John Bacchus refined it with data from the other prototypes to develop the Watcher Diary that he would use as the Eleventh when Deus held the Survival Game.

Future Diary -Another:World-
In the Drama series, the diaries work mostly the same, save for few differences: The following is a list of the known diaries in the drama series: The following is a list of diaries that are not part of the survival game:
 * The diaries are all cellphones provided by the Chronos Company, and possibly by Deus.
 * All the diaries are identical in appearance.
 * Dead End entries have two phases, the first one in which the entry appears in a red-colored background. The second phase starts so as long as nothing is done to prevent the Dead End; when the Dead End's conditions start to be met, a countdown is shown next to the entry, revealing how long the Holder has before being killed. Deus reveals the only way to evade a Dead End is to kill someone else. It is said that if the countdown reaches 0 even if nobody does anything, the person will die, although this is unknown as any chance has been interrupted by the death of another Holder.
 * The diaries have different noises depending on the diary when entries appear, however the overwriting of an entry by defying the future is similar to that of the anime series.
 * The Perception Diary (知覚日記 Chikaku Nikki): Used by Arata Hoshino. It works like Yukiteru Amano's Random Diary; it gives him entries about everything he will see or hear, but say little to nothing about himself. They vary in time intervals and can predict things that will happen very soon to later events. It reflects how he accepts everything as it is.
 * The A-kun Diary (新太君日記 Arata-kun Nikki): Used by Yuno Furusaki. It works like Yuno Gasai's Yukiteru Diary; it allows her to predict everything about Arata, but nothing about herself unless it is related to Arata. It is hinted that it also gives details of his past, although it is unknown if this is due to the diary or information that Yuno collected while stalking Arata. It reflects her obsessive love for Arata.
 * The Trust Diary (信頼日記 Shinrai Nikki): Used by Megumi Fuwa. The diary will tell her about people or events she may or may not trust. Ironically, she does not seem to trust much in her diary. It reflects her constant distrust of people.
 * The Murder Plan Diary (殺人計画日記 Satsujin Keikaku Nikki): Used by Yousuke Okuda. It works like Takao Hiyama's Murder Diary; it allows him to calculate the success chance of a plan designed to kill his victims to choose the best course of action. Presumed to range from 0%-100%, with the highest revealed rating being 87%. Even the "best" chances are not infallible, and can even give him a Dead End with even a high success chance. It reflects him as an intelligent serial killer.
 * The Evidence Diary (証拠日記 Shōko Nikki): Used by Kinjiro Hagito. It works like Keigo Kurusu's Criminal Investigation Diary, showing entries about all the evidence he will find in a crime scene and get hints to solve the crime. The diary will only activate when he gets to the crime scene. Since it only shows entries about a crime scene, his diary won't tell anything about himself. It reflects him as the detective of the police.
 * The Action Diary (行動日記 Kōdō Nikki): Used by Tohru Kibe. It works like John Bacchus' Watcher Diary, giving him entries about the actions of the diary holders. The profiles of the other diary owners are also present on Kibe's laptop and computers. It reflects him as the creator of the Future Diaries.
 * The Description Diary (説明日記 Setsumei Nikki): Used by Haruna Okie. It gives her a full description of people and/or events related to her that will happen. It can predict a lot in advance. Her diary apparently did not start until halfway through the game, although she reveals this to be a lie. It reflects her tendency to judge people.
 * The Revelation Diary (発現日記 Hatsugen Nikki): Used by Rui Moriguchi (only in the second Survival Game). It gives him entries about events he will find out and/or is not aware of. It reflects his clever personality.
 * The Family Diary (家族日記 Kazoku Nikki): Used by Kurou Hoshino. It works like Tsubaki Kasugano's Clairvoyance Diary, predicting what happens to his son and wife. However, it won't predict anything about himself unless is related to his family. Revealed to be a lesser model of the Future Diaries made by Kibe. It reflects his great love for his family.
 * The God Diary (神様日記 Kamisama Nikki): Used by Deus and the winner of the Survival Game. It allows the user to control the virtual reality of Olympia, also enabling them to have a single wish granted. It is the only diary that does not predict the future, instead being more of a reward for winning Deus's game. It reflects its user as the god of Olympia.