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.

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.