The Neighbor World

Short Summary
''Replica gives a brief explanation on the Neighborhood and the nations that might possibly attack (Liberi, Leoforio, Chion and Aftokrator) along with wandering planet nations. Shinoda offers to promote Yūma to B-Rank, but he declines. Jin asks Miwa to look out for Osamu in the upcoming battle. All of Border prepares for the attack, when suddenly countless gates open and the invasion begins!''

Long Summary
Replica explains that counties in the Neighborhood are like stars with elliptic orbits. Kuga referred to them as "planet nations." Replica goes on to say that when a planet nation revolves close to this world, they can open a gate and send their away ship. He says that one of the nations orbiting the planet right now is the one preparing to attack. Kinuta angrily states that they know this much, but they want to know which one exactly. For that, Replica asks Rindō and Shiori for help uploading his own data on the actual Neighborhood map, which is much larger than the one Border had been using. Based on the new map, Replica states that the country attacking them will most likely be one of four: Liberi, Leoforio, Kion, or Aftokrator (the largest military nation in the Neighborhood). Unfortunately, there are also "errant nations" that fly around the Neighborhood without a designated orbit. One of these countries could also attack if close enough.

Kazama then points out that an Ilgar and a contingent of Rads had been sent to Mikado City recently and were most likely a prelude to war. With this in mind, Yūma says that either Aftokrator or Kion was most likely to be the one, since few countries use Ilgar. Yūma then asks if Jin's Side Effect can't tell which country will attack. Jin explains that he cannot see the future of someone he hasn't met. Kido says they should move forward assuming it is either Aftokrator or Kion. Kido asks for more information on these countries, particularly whether or not they possess Black Triggers. Replica says that when they visited those counties seven years ago, Kido had six Black Triggers and Aftokrato had 13. He adds that Black Triggers are rarely used on away missions, and the majority of the attacking force will be Trion Warriors and not Humanoid Neighbors. Shinoda asks Osamu to notify them if he notices anything (since he was part of both the Ilgar attack and the Rad invasion previously), and Yūma to fill in any intelligence they don't know.

During shooting practice, Natsume Izuho ranks 112 out of 128, but next to her Chika ranks 41st. Chika says her mentor told her snipers to get better through practice and she could become an official agent if she wasn't lazy.

Shinoda talks with Osamu and Yūma after the meeting and thanks them for their cooperation. He relates Kinuta's estimate that the map they provided was worth 30 away missions. Shinoda mentions that he was once indebted to Kuga and encourages Yūma to come to him if he ever needs help. He adds that Kido was actually the one who knew Kuga the longest. Shinoda then offers to promote Yūma to B-Rank.

On the roof of HQ, Jin approaches Miwa and asks for a favor. Although Miwa initially refuses, but Jin asks Miwa to look out for Osamu during the upcoming battle. Jin explains that his Side Effect says that Miwa is the one who would be able to come to Osamu's aid. As Miwa walks off, Jin offers to recommend him to be Fūjin's new owner. Miwa lashes out angrily again and walks away, while Jin repeats that his Side Effect says Miwa will save Osamu.

At Tamakoma Branch, Yūma reflects on his conversation with Shinoda. He rejected the offer to move up to B-Rank without earning the position. Replica asks if it was okay to turn down the offer. Yūma says it's fine, because when he fights the Neighbors, he will be using his father's Black Trigger, not a Border Trigger. Replica warns that this could be dangerous, since Kido's words meant Yūma would be seriously punished if he ever broke Border's rules. Yūma says that if he senses he is in danger, he will definitely use the Black Trigger. Replica repeats the words he often told Yūma when they first came to Japan, that using the Black Trigger is Yūma's choice.

In the morning, Shiori offers Yūma a bento with side dishes leftover from the massive quantity Reiji made the day before. Rindō enters and asks for some as well, and Yōtarō and Raijinmaru ask for rice. Shiori attempts to open the rice cooker, but accidentally presses on Replica instead. At school, Osamu's classmates congratulate him on becoming an official agent, and they barrage him with questions. When Osamu requests and is granted leave to go on defense duty, the students are even more impressed. Exhausted from all the attention, Osamu eats lunch with Yūma up on the roof and reminisces about the day he first met Yūma and everything that has happened since. Yūma says he is also glad that Osamu was the first person he met. Osamu then remembers that Yūma's real body is slowly dying inside the Black Trigger. Chika and Izuho join them on the roof, and Izuho asks Osamu if he is going out with Chika. Osamu quickly denies it, saying they are just childhood friends, and thinks about the promise he made to Rinji to look after Chika.

Osamu asks Yūma about the invasion circulation sent to the C-Rank agents, and Yūma explains that although they aren't allowed to fight, C-Rank are allowed to use their Triggers for evacuation or rescue (thanks to Osamu's actions during the Ilgar incident). Izuho incorrectly guesses that Yūma is the leader of their team, but says she likes Osamu upon learning he is the leader. He asks Izuho to look after Chika, reminding Yūma of Osamu's explanation that he fights for the sake of others. Yūma says that Kion and Aftokrator will move out of range in ten days and they should endure it until then.

Elsewhere in Mikado City, Jin sits on a rooftop and remarks that they are early. A warning sounds at HQ, and a large number of gates suddenly appear over the city all at once. Shinoda immediately orders for the emergency summons of all off-duty agents and orders the commencement of a full-force counter-attack.

Adapted From

 * Chapter 42
 * Chapter 43