Haruaki Azuma/Plot

Background
Azuma joined Border after it went public, approximately four years before Chika Amatori and Yūma Kuga enlisted. He was Border's first Sniper and together with the members of the first generation of Azuma Unit he climbed to the #1 position in A-rank. At some point in time Azuma was selected for an away mission to the Neighborhood and was told about Cronin being a Neighbor. The members of the unit except for Azuma himself left it in unknown circumstances, to be replaced by Yukimaru Ichijō, Takaaki Katagiri and Karin Yuitsuka. Eventually, Azuma Unit reached its current composition, which in Noboru Koarai's case was due to him clinging to Azuma's leg for over an hour. Apart from his teammates, Azuma took on a great number of students in both strategy and sniping, such as Mirai Hatohara, Reiji Kizaki, Tōru Narasaka, Isami Tōma and Ren Tsukimi.

Introduction Arc
Azuma Unit was presumably involved in the extermination of all Rads in Mikado City.

Border Enlistment Arc
On the official Border enlistment day on January 8 Azuma is one of three Snipers, the others being Tetsuji Arafune and Ken Satori, serving as instructors to the new recruits. He is puzzled by Chika asking him if she has to run after shooting, to which he replies that she doesn't. The other trainees are amused by her enquiry, but, since that aspect of sniping is taught only to B-rank, Azuma infers that her mentor believes her to be capable of climbing up the ladder. After she inadvertently punches a hole in the base while trying out Ibis, he assures her that there is no problem and says that Satori, as the supervisor, will take the blame, which he reaffirms when she fears that he people at Tamakoma Branch will get in trouble on her account. When a furious Motokichi Kinuta barges in and starts venting on Satori, Azuma explains what transpired. Seeing him soften as he talks to Chika, Satori assumes that he has a soft spot for little girls, with Azuma remarking that she probably reminds him of his daughter. Concluding that Tamakoma Branch chose not to report her trion levels to enhance the shock, he assumes either Yūichi Jin or Takumi Rindō to be responsible.

Large-Scale Invasion Arc
Azuma Unit is deployed by Masafumi Shinoda to prevent the initial wave of Trion Warriors sent by Aftokrator from reaching Mikado City. Border's traps buy them enough time to arrive on the scene, which Azuma reports as he shoots down a Bado the successful suppression of the Trion Warriors. Just as Azuma Unit is about to go support other units after disposing of the Trion Warriors in the area, he notices a Rabbit emerging from a carcass and hears more Trion Warriors approaching. As soon as Tsuneyuki Okudera takes his eyes off the Rabbit, it attacks him and sends him crashing through multiple houses. Azuma warns Koarai to wait for their teammate before taking it on, but Koarai does not listen and is quickly immobilized by the Trion Warrior. Azuma attempts to shoot it, but the creature deflects his blast. Azuma then changes targets to Koarai, saving him from capture by forcing him to bail out. He then tells Shinoda about the Rabbit and its goal to capture agents.

Shinoda orders the other B-rank units to meet up with Azuma, and Taichi Betsuyaku reaches him moments before Lamvanein is warped right next to them. Azuma tells Betsuyaku to fall back and lure him into their range, taking note of the irregular Gate he came out of. Chano Unit attacks him, but before Azuma can warn them that Lamvanein is about to open fire, the Neighbor obliterates their trion bodies. Azuma and Betsuyaku run away, but, contrary to Azuma's expectations, Lamvanein rapid-fires at them, causing the Suzunari First Sniper to bail out. Arafune Unit attempts to snipe him, but he defends and his retaliation removes Yoshito Hanzaki and Atsushi Hokari from the battle. Azuma manages to get away, but even as more B-rank agents join him, they are still forced into hiding by Lamvenein's superior firepower, with Azuma wondering if the deadlock was what the enemy wanted to free up the Rabbits in the south.

When Kōhei Izumi, Shun Midorikawa and Yōsuke Yoneya join the fight, Azuma describes Lamvanein's Trigger. After Midorikawa cuts off his leg, Izumi lures the Neighbor towards Arafune and Azuma, who manage to shoot off pieces of Chelidon. Noticing that he now has less focus to spare, Azuma advises his allies to capitalize on their numerical advantage and pressure him until he shows an opening. This decision results in Lamvanein's eventual defeat, immediately after which he is rescued by Mira, whom Azuma identifies as a Black Trigger user. He instructs his allies not to give chase. B-rank agents are then assigned to defending the southern area, while the A-rank agents go help the trainees. Azuma thanks them and promises to treat them to a meal, a promise which he honors after the invasion is foiled. As a result of his actions, he is the recipient of an Outstanding Distinguished Service award as well as a Distinguished Service award as part of Azuma Unit.

B-Rank Rank Battles Arc
Azuma is invited as a commentator for Tamakoma Second's match against Arafune Unit and Suwa Unit. He is surprised by the map chosen by Tamakoma Second, as Cityscape C greatly favors Snipers. After the match begins, Azuma realizes that the selection was prompted by the unit wanting to form a natural alliance with Suwa Unit against Arafune Unit. He continues to analyze and describe the match and, after its conclusion, gives his overall commentary, focusing in particular on Tamakoma Second. When Shōhei Kodera explains to Futaba Kuroe just how decisive the unit's strategy was, Azuma light-heartedly comments that he has nothing to add.

On February 11 Azuma listens to Koarai and Okudera squabbling over the complexity of the map to pick against their opponents in the upcoming match. After prompting them to share their analysis and ideas in a coherent fashion, he voices his preference for a simple map before making sure they remember his tenets and exhorting them to create a winning strategy. Some time later, he authorizes Koarai to tweak the weather conditions. They eventually settle on Cityscape B with a snowy terrain.

On Saturday February 15, once the battle starts, Azuma spawns in the eastern area of the map, hidden with a white Bagworm. He spots Yūma and Sumiharu Inukai, and recognizes a third trion signature as Osamu Mikumo's from his movements. When Inukai engages Osamu, Azuma begins to move towards them. After two Attackers of Azuma Unit as well as Shinnosuke Tsuji converge into the building the battle has moved to, Azuma takes out the captain of Tamakoma Second by sniping through the walls. He moves away after the shot, and, when Chika opens fire, he rushes towards her, preventing her from bailing out on her own and taking note of her position for his teammates, although Kageura Unit allows her to flee. The Attackers of all four units begin a melee fight during which Azuma manages to shoot off Yūma's leg. He notices Yuzuru Ema bailing out and sees Hiro Kitazoe's Meteor shower, which he intercepts before targeting him directly. Masataka Ninomiya however shields Kitazoe before defeating him himself. Caught unawares, Azuma is unable to intercept the Gunner's final round of explosives. A few minutes later, only Azuma, Masato Kageura and Ninomiya survive. The Sniper is keen on running out the clock unless either opponent makes a move, and tells his teammates that the snow ended up working well for the map.

The following day, Azuma is invited by Shinoda to an emergency response meeting to address the possibility, mentioned by Enedrad, of an impeding attack from Galopoula or Rodochroun. When Jin states that he hasn't seen any agents or civilians being abducted or killed, Azuma speculates that the enemy is interested in something else, such as tech or intelligence. To the surprise of the agents present, Masamune Kido announces that the interception will be carried out confidentially. Azuma suggests enlisting Tsukihiko Amō's help, not to have him fight but to rely on his Side Effect. After the meeting he catches up with Kyōko Sawamura before asking Shūji Miwa if he's eating enough and inviting him out for a meal. On the night of Galopoula's blitz, Azuma Unit fights a rank battle against Kageura Unit and Yuba Unit.

The members of Azuma Unit then meet up to strategize ahead of their match against Tamakoma Second, Kageura Unit and Suzunari First. In the few minutes before the battle begins, Tamakoma Second is revealed to have added a new member, whom Koarai recognizes from having sparred with him a few days before. Azuma exhorts his teammates not to lose heart, as gaining experience dealing with the unexpected is the point of rank battles. Shortly afterward, the map chosen by Suzunari First is revealed to be Cityscape D. Koarai and Okudera discuss the map selection, which Okudera senses to be motivated by something other than a decision to obstruct enemy Snipers. Azuma observes that that feelin is important, as sometimes instinct can precede reason. He then comments that the match will test their ability to improvise and, after making sure that they remember one of his tenets, thinks to himself that the battle will allow him to gauge their growth.

Azuma spawns right next to the central mall and immediately dons his Bagworm. Azuma ponders whether to observe the other teams from outside or go into the mall, and in part due to the night setting opts for the latter. When Okudera tells his teammates that he is engaging Osamu, the other members of Azuma Unit begin to converge on the two fighters. However, as the clash moves to the upper floors and Osamu manages to escape, Azuma stops his chase and begins scattering Dummy Beacons throughout the mall. He warns Koarai and Okudera when he spots Hyuse and Yūma vaulting towards the top floor. The two catch Ema in a pincer attack which forces him to escape by letting himself fall towards the atrium, but he is sniped mid-fall by Azuma.

The three members of Azuma Unit proceed to target Hyuse and Yūma, who, together with CHika, are the only opponents left. Koarai and Okudera close in on the two from the south, Azuma from the north. As he does, he has Mako Hitomi assist him with the Dummy Beacons, which they turn on. In response Chika blows up half of the mall, accidentally removing Okudera from the fight and injuring Koarai's foot. When they are shocked by the development, Azuma points out that they cannot rely on their opponent not being able to shoot, and asks them what he should do next. Okudera correctly responds that he should stay close to Hyuse and Yūma to avoid being hit by a second round. Azuma then asks them what their best course of action is, while Hyuse seals off the exits. Okudera opts for full retreat, and Koarai begrudgingly agrees. To allow Koarai and himself to get far enough from Tamakoma Second to be able to bail out on their own, Azuma takes control of some of the beacons and sends them towards Chika's general location before turning them off in an attempt to rattle Osamu and have Hyuse and Yūma relinquish their position. As a result, Yūma heads towards Chika while Hyuse continues to hunt down the opponents inside the ruins of the mall.

Azuma thus sets a trap by attaching his Bagworm to his Lightning and having it hang off the edge of the first floor, while disguising his own trion signature with a Dummy Beacon's. When Koarai lures Hyuse in the right spot, Azuma switches from Lightning to Ibis, causing the Bagworm to fall and catching Hyuse's eye. The opponent fires half of his bullets at the cloak, giving Azuma an opening to inflict fatal damage; however, Hyuse manages to injure Azuma's leg before bailing out. The Sniper tells his teammates that their next move ill be determined by Tamakoma Second's. As a Meteor barrage rains down on the remains of the mall, Azuma urges Koarai to bail out and does the same, decreeing the end of the match. Despite the commentators' praise of their decision, Koarai feels like all he could do was run away, but Azuma interjects that both Attackers properly judged the battle and authorizes them to equip Triggers to their Sub.

Right after the match, Azuma is summoned by Eizō Netsuki to decide how to best deal with the rumor, spreading among trainees, that Hyuse is in fact a Neighbor. Netsuki decides to manufacture a different rumor, specifically that Hyuse is from Canada and that he had been training in secret with Tamakoma First for years to replace Jin, only to be added to Tamakoma Second instead when Jin stopped using Fūjin. As the two explain to Osamu, who soon joins them, Azuma agrees to begin spreading it at joint Sniper training the following day through other official agents, who will cite Azuma as the source of the rumor; if asked, Azuma will concede that the rumor is plausible without confirming to be the source. Should Hyuse's identity eventually be revealed, Azuma is to say that Netsuki ordered him to lie. The two proceed to notify agents who already know about Hyuse's and Cronin's provenance.

The meeting is adjourned, and Osamu apologizes to Azuma for causing him to be involved. Azuma is unconcerned and tells him that agents who had been to the Neighborhood, like himself, already knew. He then proceeds to enquire about Chika's condition after the match, since Hatohara, who, like Chika, was unwilling to shoot others, had a severe reaction the one time she accidentally hit someone in a rank battle. Despite acknowledging that the circumstances may be different, he advises Osamu to keep an eye on Chika. He then confesses that, after being told that the rank wars would end after the eighth round, he did not believe that Tamakoma Second would be able to make the cut for the expedition. Netsuki comments that Azuma should not be rooting for any specific unit, to which the Sniper responds that he is simply amused by the manner of Tamakoma Second's ascent through the ranks. When Osamu apologizes before leaving, Azuma and Netsuki are both impressed. Netsuki floats that he might be trying to save his reputation, but Azuma lets him know that he tried to recruit Jin into Tamakoma Second, from which they can infer that Osamu does not care about it. Azuma notes that though he does everything he can to help others, he does not think about himself at all. The following day the rumor is successfully planted, as Azuma and Osamu report to Netsuki.