Rin Kagami/Plot

Background
Kagami joined Border around three years before Yūma Kuga and Chika Amatori. While it is unknown when Arafune Unit was created, it occurred when Tetsuji Arafune was still an Attacker, so a little over eight months before the unit's match against Tamakoma Second and Suwa Unit at the latest.

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

Large-Scale Invasion Arc
Kagami presumably assists her teammates during Aftokrator's invasion. After its end, Arafune Unit becomes the recipient of an Excellent Distinguished Service award. Kagami is either present at or later watches the press conference during which Osamu Mikumo discloses the possibility of a rescue mission in the Neighborhood.

Round Two
On February 2, three days before Arafune Unit's match against Tamakoma Second and Suwa Unit, Kagami digs up data on Yūma's and Osamu Mikumo's solo matches against Shun Midorikawa, though she does not recognize Osamu until Atsushi Hokari mentions the press conference. Arafune tells her to gather all the information she can find. On the day of the match she is surprised that Tamakoma Second would pick Cityscape C as the stage, since it favors Snipers. The movements of Tamakoma Second distract her and she fails to notice that the members of Suwa Unit have activated Bagworm at first, but she manages to warn her captain in time for him to avoid a lethal sneak attack from Kōtarō Suwa. After Yoshito Hanzaki's failed pickoff attempt against the enemy captain, Kagami warns him about approaching enemies, which he takes to mean Daichi Tsutsumi. She corrects him just as Yūma climbs up behind him. Not long afterwards she tells her teammates that Suwa and Hisato Sasamori have both disappeared from Radar. At the end of the match she congratulates Arafune on his performance.

Round Three
A few days later Arafune Unit fights and wins a rank battle against Kakizaki Unit.

Galopoula's Blitz
On the night of February 19 Kagami presumably assisted her teammates during Galopoula's incursion.