Aru Akise

Aru Akise (秋瀬 或, Akise Aru) is one of Yukiteru Amano's friends, and later becomes one of the main characters of the series. Aru is very intelligent and dreams of being a world famous detective when he gets older. Investigating the connections between Yukki and the diary owners, Aru becomes a close ally to Yukki, but an enemy and rival to Yuno Gasai. Aru realizes Yukki is seemingly the best fit and wishes for him to become God. He is the main character of the spin-off manga Future Diary: Paradox, where he and Muru Muru replace Yukki and Yuno in the survival game after Muru Muru accidentally kills Yuno Gasai while Yukiteru is injured.

Appearance And Personality
Aru is a boy with white hair and reddish-pink eyes. In his first televised appearance he wears a blue jacket over a white dress shirt and black tie. He wears grey pants and black dress shoes. All of his subsequent outfits are some variation on this.

Aru is intelligent and logical. Although he was surrounded by people who had future-predicting diaries, he was able to outsmart them. He's also extremely observant, noticing small details, putting them together, and using them to his advantage. He is also very calm and somewhat reserved with his emotions.

Aru is quite social; he doesn't hesitate to befriend those who he's only known for a short amount of time, including people who previously rivaled him, which shows how understanding he is. For instance, although Yuno attempted to kill him on multiple occasions, he still tried to understand and cooperate with her until she kidnapped Yukiteru.

Although it is shown on many occasions that Aru genuinely cares about people and wants to help them, he is not above using manipulation and breaking the law to get what he wants. Throughout the series he constantly lied and concealed the truth, broke into Yuno's house, and cooperated with Minene Uryu (a known terrorist).

Diary & Abilities
Near the end of the Survival Game, Aru receives the Detective Diary from Kamado's Server Diary. Taking the form of a slim cell phone, this Apprentice Diary allows him to read the predictions of other Diaries (similar to John Bacchus's Watcher Diary), as well as giving him predictions about their actions. This makes the Detective Diary one of the most powerful Diaries in existence, as it enables Aru to outmaneuver any other Diary users. Despite this incredible advantage, it does have weaknesses; if someone already knows the predictions on his Diary, they can find ways to manipulate the outcome to favor them.

Throughout most of the series, Aru relies on his great intellect to solve things. Befitting the detective he aspires to be, Aru is quite smart and can deduce things easily with small bits of information. For example, when Karyuudo sent his dogs on a killing spree, Aru was capable of tracking him. He also could figure out that Yukki's Random Diary worked based on his perspective, after seeing it in action only once.

Being a detective, he has strong ties with the police mostly with Masumi Nishijima; this gives him access to resources used by the police, including confidential information and also the policemen themselves, evidenced through how he could figure out Yukki was a common variable throughout multiple incidents with the Diary Holders, as well as have the police guard different places. Nishijima even seems to rely on Aru's judgment throughout the Diary Game.

Aru has proven himself to be skilled in hand-to-hand and melee combat, as he was able to overpower Yuno even when she had pinned him down with a knife to his throat. While he is mostly seen without a weapon, when it comes to fighting he does have a preference for bludgeoning weapons like tonfa or a pipe. He is roughly on par with Yuno in terms of combat skill.

Possibly as a result of his supernatural origins, Aru is highly resistant to injury, able to survive a slashed throat and even continue moving after being completely decapitated.

History
Aru Akise, also known as the Observer, was at some point directly created by Deus in preparation for the Diary Game. His intended role was to witness the events of the game and to interfere with in a way that corresponded with Deus' goals. It is implied that with these goals in mind, Aru was bestowed an inquisitive personality and made to protect Yukiteru. He was given no knowledge of his supernatural origins.

Before the game begins, Aru lives a fairly normal life. He attends school and lives in an ordinary house. And in Future Diary: Paradox it is shown that Aru has parents, but their origins are unknown.

Future Diary: Paradox
Aru Akise is contacted by Muru Muru after she accidentally removed Yuno Gasai before the start of the survival game.

The Tenth's Trap
Aru makes his first appearance in the anime as Yuno Gasai and Yukiteru Amano walk down a street on the way to their new school. Yukiteru notices Aru standing across the street, watching the two of them. Aru smiles at Yukki and disappears before the latter can bring Yuno's attention to him.

That afternoon, Yukiteru, Yuno, Mao, and Ouji Kosaka are confronted by a vicious pack of dogs who they believe killed Hinata. Aru appears from the trees behind them, saying that he's been following the group and wants to help them out. Mao recognizes Aru as being part of their class. Aru caresses Yukki's face and tells him not to worry or mistrust him, because they're friends. Aru then suggests that they head to the observatory nearby.

Once they've entered the observatory, Aru introduces himself to Yukiteru again, stating that he wants to be a world-famous detective someday. He reveals that he already knows Yukki's name, because he's been investigating various incidents (related to the diary game) and noticed that Yukki was involved in all of them. He decided that although Yukki was probably hiding something, he is a victim who should be protected from now on. Yukki is relieved and decides that Aru is a good person.

Yuno believes that Aru is the most likely suspect for being the controller of the dogs. Yukki rejects this idea and decides to use his future diary to predict from where the dogs will try to enter the observatory. Aru helps block the windows along with the others.

After the dogs give up, Mao suddenly confiscates Yukki's future diary and puts a knife to his throat. Hinata enters the room, revealing that she had faked her death and was alive all along. She states that she hadn't wanted Yukki's diary in the first place, and that her whole plan had been to draw out Aru in order to kill him with her dogs. She states that Aru is also a diary user, and had just been concealing this fact.

It is revealed that Karyuudo Tsukishima, the Tenth, had been sending his dogs after potential diary users. Aru investigated these deaths and began to follow Tsukishima around to keep an eye on him and confirm his suspicions. Tsukishima thought Aru was a diary user, and his daughter Hinata Hino had decided to lure and kill him.

Aru proposes a game to Hinata. He flips a coin, and Hinata has to guess which hand it's in. If he wins, then Yukiteru and his diary go free, but if Hinata wins, then Aru forfeits his "diary" and life. Hinata agrees to play since she has Yukki's powerful Random Diary, but in the trial round Aru wins because of guessing and some meddling on the part of Yukiteru and Yuno. Aru plays it off like his "diary" told him the answer, causing Hinata to believe that Aru's diary can read her predictions.

Thus, in the next round, Hinata does the opposite of what the Random Diary tells her, causing Aru to win yet again. Hinata lets Yukki go, but keeps the diary, wanting to play one more round. Yuno is suspicious, so she takes Aru down and reveals that his phone has no diary written in it, and everyone else is shook. Aru laughs it off and says that he pretended to be a diary user for fun. Yuno sees this as gambling with Yukki's life, so she tries to kill Aru, but he overpowers her.

To everyone's surprise, Aru still wants to play the last round. Aru sets up a plan with Yuno, and she agrees to go along with it, but makes it clear that she doesn't trust him. In an attempt to gain her trust and show the sincerity of his motives, Aru confesses to her that he has a crush on Yukiteru. Yuno is dismayed by this revelation.

Earlier that day, Yukki's diary had predicted that he'd find Hinata's corpse, but it was revealed later on that it wasn't really her. Aru noticed this discrepancy in Yukiteru's predictions, and decided to use it to his advantage in his plan. He is successful. Instead of surrendering, Mao takes out a knife, but Yuno runs and stabs her first. Hinata tends to the unconscious Mao while the others escape. Hinata is livid and sends her dogs after the group, regardless of her promise to let them go free. Yukki wants to go back and convince Hinata to call them off, so Aru proposes that he, Kosaka, and Yuno distract the dogs so Yukki can safely get to her. Yukiteru pacifies both Hinata and Yuno, and all the kids are left alive.

The End Begins
With Kamado's help, Aru speaks directly with the dying Deus, asking him if it is possible to truly resurrect people. Deus answers that it is impossible; while the body can be resurrected, the soul can never be brought back. With this newfound knowledge, Aru realizes that Yuno has been lying to Yukki and decides to warn him; however, Deus stops him and reveals the truth of his origins. Aru denies that he was just a puppet, claiming that he has a will of his own, to which Deus challenges him to prove it. Aru says that he investigated both Karyuudo and Yuno out of his own will, but Deus says that Karyuudo was trying to evade the game and that Yuno is the most important person in the game. Deus gives one final chance to Aru, where Aru replies that his love for Yukki is his own, but Deus claims it is fake before banishing him. However, Aru manages to return after successfully receiving his Detective Diary from Kamado, which he uses as evidence of his own free will. Amused, Deus agrees to let him do as he pleases.

Aru is later found by Yukki and Yuno, stating that the Eighth is in a safe place. Yuno asks for her location, but Aru mockingly says that he wants to talk with Yukki and that she should leave. Angered, Yuno stabs Aru, but he has a protective vest; Yuno tries a stun-gun next, but Aru uses a rubber glove to block it. Yukki and Yuno are shocked by his preparations, since Yukki's Diary confirms his death at Yuno's hand; in response, Aru reveals his Detective Diary to them, explaining that it renders theirs useless. Yuno urges Yukki to go after Kamado while she fights Aru, and he does so. Aru fights Yuno and wins with the help of his Detective Diary; however, revealing its powers allows Yuno to come up with a countermeasure. With Aru pinning her down, she suddenly stabs herself, pointing out that Yukki would hate Aru if he left her for dead. Confused and shocked by Yuno's actions, Aru bandages her stab wound before leaving to meet with Yukki.

On his way to Yukki's location, Aru tries to call Yukki on his cellphone, only to find that the line is busy. He belatedly realizes that Yuno is calling Yukki and redoubles his pace, only to find himself too late; believing that his friends are trying to betray him, Yukki has killed Hinata, Mao, and Kosaka in an attempt to kill Kamado. (In the manga, Aru arrives in time to see Yukki kill the latter two; in the anime, he only arrives after all three are dead.)

Despite the tension of the situation, Aru approaches Yukki calmly, admitting that it was a mistake to let Yuno live and resolving to kill her in a few minutes as his Diary predicts. Noting that Yukki's gun is out of bullets, Aru expresses his belief that Yuno intends to become God by killing Yukki once Kamado is dealt with; in turn, a wounded Yuno arrives and warns Yukki to get away from Aru. Using the First's moment of confusion, Aru kisses Yukki and reiterates his desire to protect him before jumping down to confront a furious Yuno. Seeing her Diary in her hand, he uses a metal pipe to shatter it; much to his shock, Yuno continues forward and slices his throat, declaring that she had tricked Aru into destroying a "fake" diary.

Reeling from Yuno's deception, Aru looks at the "fake" diary's dying screen and sees an entry from Yuno's Yukiteru Diary - however, it refers to Yukiteru as "Amano" rather than "Yukki". He quickly deduces that the destroyed Diary must have belonged to the "real" Yuno, despite her not being chosen for the Survival Game; reviewing the apparent impossibility, Aru suddenly has an epiphany about this "Yuno's" real secret. Unable to speak due to his throat injury, he staggers towards Yukki, typing his revelation on his own diary in order to show him what he can no longer say aloud. Despite being decapitated by Yuno, his body continues walking towards Yukki, showing him "Yuno Gasai's" secret on the screen of his phone before Yuno manages to destroy it. A day later, Yukki questions Yuno about what Aru showed him, setting the final confrontation into motion.

Third World: OVA Redial
After the incident in the Second World, Aru Akise works for Deus as an observer for the twelve diary holders. The Third World is living in peace without the incident and massacre that happened in Second World. Deus' power is still dying, but he hasn't found a new God to take his place and even planned out a new game.

Aru, Yuno, Mao, Hinata, Kosaka and Reisuke (being his assistant) were all out for Summer class excursion when Yuno realizes that something is missing from her. Aru reports this to Deus.

Yuno was sitting on her bed when a voice started talking to her. She then started talking to her and brought her to the God's realm of Time and Space. Meanwhile, the Third World Murmur was talking to Deus when she suddenly sensed someone got in the forbidden area. Yuno started walking to the platform, following the voice in her head until third world Murmur stopped her. Uryuu used her powers (obtained from the Second World Deus) to stop third world Murmur from interfering with Yuno.

After Yuno got past third world Murmur, she sees Aru standing in the middle blocking her way. Aru starts telling her about her First World's personality and what she did to the Second World. Aru charges with a katana at Yuno, Yuno stops him and falls together on top of him. Yuno took the katana and kept walking until she saw the sphere, where First World Yuno locked Yukiteru (a world created by her for Yukiteru's wishes and desires to happen). From there, she saw the first world Murmur. Murmur starts crying and talks about her old master, First World Yuno, to her and how her memories shouldn't vanish in vain. Yuno accepts her First World memories.

Meanwhile, Yukiteru's Future Random Diary bleeps and show 'Yuno went to see Yukiteru'. Yuno went to the Second World's realm and hugs Yukiteru. Third World Deus made Yuno to be the third world's Goddess, making a pathway for Yukiteru and Yuno's realms.

Trivia

 * Aru's character theme song is "Song of A Certain Truth" by Alice Rokugen. It expresses a desire to protect a certain person from the hardships and lies of the world, and to live a peaceful life with that person forever. It also meditates on the nature of Truth, wondering what counts as the truth and whether it's better to know nothing and live in peace.
 * His given name, Aru, can mean "exist" if written with different kanji, which could be a subtle hint to Aru's true origins.
 * In Paradox, Aru's brief alteration of history allows him to create a large alliance made out of most of the diary owners - Keigo Kurusu, Reisuke Houjou, Tsubaki Kasugano, Marco Ikusaba and Ai Mikami, Kamado Ueshita being represented by Orin Miyashiro, and Yomotsu Hirasaka. He never meets Karyuudo Tsukishima and John Bacchus, kills Takao Hiyama and fights Minene Uryu.
 * In the Japanese dub of the anime, Aru's voice is deeper than Yukki's. However, this is reversed in the English dub.
 * Aru isn't in love with Yukiteru, despite Aru kissing Yukiteru to make Yuno jealous and charge at him. However, the extent to which this friend-love is Aru's own is unclear; when Aru tells Deus that he loves Yukiteru, Deus tells him it was also part of his plan.
 * Third World Aru is called an Observer by Third World Murmur and Deus.
 * Incidentally, the Detective Diary's ability is the same ability Aru pretended to have when he faked being a Diary user against Hinata.
 * In the Third World, Tsubaki has her eyes on him and is a complete stalker.
 * Aru Akise is very similar to Nagisa Kaworu from the Evangelion franchise, particularly their love for the protagonist & close relationships with them. They also both have white hair, red eyes, holy origins, and are both voiced by Akira Ishida.