B-Rank Wars Arc

The B-Rank Rank Battles Arc is the fifth arc of the World Trigger series.

A Flashy Debut
Osamu meets Kido in the hall, and they discuss the press conference. Osamu reveals that he is aware that Kido had intentionally used him as a scapegoat. He warns Kido to never use Yūma and Amatori like that, lest be deprived of his forgiveness. Kido complies and simply wishes Osamu good luck. Karasawa and Jin also discuss this, with Karasawa telling Jin that he wanted to give Osamu a chance to defend himself. He also divulges the increase in applications to Border since Osamu's outburst. Mikumo Unit makes its debut fighting against Yoshizato Unit and Mamiya Unit. Though Osamu is unable to participate due to his wounds, Yūma and Chika easily outdo their foes. It is a stunning victory, which attracts the attention of unsuspecting spectators. The team rank goes from #21 to #12, and their next Rank Battle will be against Suwa Unit and Arafune Unit. While they celebrate their victory, Konami alerts them that their next two opponents would be much stronger. The three participating teams begin analyzing each other, and on February 5, they have their second Rank Battle of the season.

Tamakoma Second vs. Suwa Unit vs. Arafune Unit
As the stage is Mikumo Unit's decision, Osamu chooses City C, a neighborhood sitting on a hill. It is initially met with surprise, as it would benefit the Sniper-oriented Arafune Unit. However, one of the battle's commentators, Azuma, reveals that his would force Suwa Unit to create an alliance with Mikumo Unit in order to prevent Arafune Unit from getting the advantage. Chika hides while Osamu and Yūma move on the offensive. Yūma goes to attack Hanzaki, but the two are shot at by Tsutsumi. While Yūma dodges the attack, Hanzaki is hit and Bails Out. Tsutsumi attempt to shoot Yūma, but Yūma dodges with his newly-gained Grasshopper and cuts him down. Yūma sets his sights on Hokari, but Arafune intercepts him and fights him with Kogetsu. Eight months before, Arafune had been a renown Attacker; however, he switched to being aa Sniper. Hokari supports his captain, giving Arafune the advantage. However, Sasamori comes intent on defeating Hokari. Osamu circles the battle zone, exerting pressure just by being there. Hokari decides to shoot Yūma, even though it means certain defeat at Sasamori's hands. Yūma is injured, and as he thought, Sasamori cuts him and he Bails Out. Yūma tricks Arafune into thinking that he would escape with Grasshopper, but uses the Trigger to launch himself towards his opponent and cut off his feet. Suwa comes to attack, and Sasamori, using Chameleon, traps Yūma for Suwa to get a clear shot, despite the fact that Yūma could stab him. Usami cues Chika to shoot at this moment, saving Yūma, but Arafune uses the opportunity to snipe back, hitting her and she Bails Out. Arafune and Suwa being attacking Yūma, but Osamu appears to shoot the two down, eliminating them, and giving Mikumo Unit the victory (6-2-1).

Tamakoma Second vs. Nasu Unit vs. Suzunari First
Following their second Rank Battle, Mikumo Unit moves to #8. Their next Rank Battle is against Nasu Unit and Kuruma Unit. Yūma and Midorikawa have a Rank Battle, in which Yūma dominates. Arafune comes along, and challenges Midorikawa for announcing his prediction that Arafune would lose the Rank Battle. However, before that, the No. 4 Attacker Kō Murakami comes along, with Midorikawa stating that he was the reason Arafune quit being an Attacker. He asks Midorikawa to fight him, but Midorikawa states that he can't afford to lose any more points, capturing Yūma's interest. Yoneya also refuses to fight, saying that he wants to fight a Grasshopper user. Yūma himself volunteers, much to the others' disapproval. Murakami agrees, but with 2 conditions: the battle is 10 matches long, and there will be a 10-minute intermission between the fifth and sixth match. Yūma accepts. In the first 5 matches, Yūma wins four times, which makes Osamu think that he should center the team strategies on Yūma. However, Yoneya advises him to keep watching. Murakami wins five times in a row, becoming the first person to beat Yūma in battle. He reveals that he has a Side Effect of "enhanced sleep memory", where he synthesizes information extremely accurately when sleeping. Yūma's loss surprises those in Tamakoma, but the fact he got 40% of the points impresses both Murakami's team Kuruma Unit, as well as Mikumo Unit's other opponents, Nasu Unit. The Rank Battle begins on Saturday.

The stage is the riverside one, in stormy weather. The map is composed of two segments of a city divided by water and connected only by one bridge. This is most likely to subdue Chika's Sniping abilities. None of the teams have all members on the same piece of land, making the bridge a central location. Nasu Unit's strategy hinges on them being able to group at the bridge before the other teams. However, this is quickly interrupted when Chika blows up the bridge. Unable to regroup, Nasu decides to clear her side herself, while Kumagai is approached by Murakami. She puts up a fierce fight, but is unable to keep up and Bails Out. Hiura attempts to shoot Yūma, but she misses, inadvertently giving her position away, and Yūma cuts her down. Yūma and Murakami are the only ones remaining and begin their fight. It seems to be an even battle, but slowly tipping in favour of Murakami. Seeing that using old techniques is useless against the latter, Yūma has Murakami step onto a Grasshopper to launch him into the river, where Yūma stabs him and defeats him, but is now stuck in the river.

Meanwhile, Nasu begins to barrage the opponents on her side, and manages to take out Betsuyaku and cripple Kuruma. She gets locked into a fight with him. Osamu has Chika break the dam, releasing the river water into the city. This bogs down Nasu, who has been relying on her maneuverability. Nasu manages to defeat Kuruma with Tomahawk, but before he Bails Out, he shoots Hound bullets. The bullets hit Nasu, severing her arm. Osamu uses this moment to try and claim a point by defeating Nasu. The attack is in vain as Nasu purposely had several Tomahawk bullets miss Kuruma so that they could be used against Osamu. Osamu Bails Out, but Yūma approaches, having survived the river. With significant Trion loss, Nasu is forced to Bail Out, giving Mikumo Unit their third victory.

The Attack on the Ship
Following their loss against the upper B-Rank teams, Osamu asks Jin to join their team. When Jin asks Osamu for his reason, Osamu states that he wanted to go on the expedition more quickly since Yūma was running out of time before his death and he wanted to reunite him with Replica. Jin refuses because there were other things to which he had to attend. Later, Jin goes to a meeting where the subject of another invasion is brought up. Two of three planetary nations coming near Earth are vassals of Aftokrator. Due to their small size, an all-out invasion would be unlikely, so a covert mission could happen. Additionally, Jin did not see any casualties happening in many citizens' and Border agents' futures. Just in case, a special barrier is in place until the planets leave Earth's proximity and the A-Rank units are on alert. Enedra explains that because Aftokrator would have to deal with their internal issue of choosing a god, Hairein would send those two countries to do their work.