Aki Hiyami/Plot

Background
Hiyami joined Border approximately two years before Chika Amatori and Yūma Kuga. She eventually joined Ninomiya Squad, rising to A-rank and at one point passing the selection for the Away Team; however, Mirai Hatohara's inability to shoot others caused first her, then the whole squad to be removed from the force. On May 1, the team dined together at a barbecue restaurant to celebrate Sumiharu Inukai's birthday; shortly afterwards, Hatohara ventured into the Neighborhood with her accomplices, causing Ninomiya Squad to be demoted to B-rank as punishment.

Introduction Arc
Ninomiya Squad presumably takes part in the extermination of all Rads in Mikado City.

Large-Scale Invasion Arc
Due to Masafumi Shinoda preventing B-rank Squads with missing members from fighting against Aftokrator's forces out of fear of capture, Ninomiya Squad is not deployed.

B-Rank Wars Arc
Ninomiya Squad fights the first round of Rank Wars on February 1.

Round Two
Since Azuma Squad, Katori Squad, Ōji Squad and Yuba Squad compete in a four-way rank wars in the day division on February 5, and Ninomiya Squad is known to have clashed with Ikoma Squad on that same day, the battle presumably took place in the night division, with Kageura Squad as the third team.

Round Three
On Saturday February 8, Ninomiya Squad competes in the third round of rank wars.

Round Four
On February 15, during the night division of rank wars, the match between Kageura Squad, Ninomiya Squad, Azuma Squad and Tamakoma Second begins in a snowy Cityscape B. Noticing the small number of trion signatures on Radar, Hiyami infers that the members of Azuma Squad are wearing Bagworm and hypothesizes that they might have equipped Grasshopper to outmaneuver everyone else. After Masataka Ninomiya corners Yuzuru Ema, Hiyami confirms his hit. He requests the map of the building the Sniper fled into before reassigning her to supporting Shinnosuke Tsuji. The match ends with Ninomiya Squad in the lead with three points. They retain their position at the very top of the ranking.

Galopoula's Invasion
Since Azuma Squad, Kageura Squad, and Yuba Squad fight in the night division of rank battles on February 19, Ninomiya Squad must have competed in the day division against Ikoma Squad, Ōji Squad and Suzunari First. They continue to rank first at the end of the match.

That night, Ninomiya Squad defends Border's Headquarters against Galopoula's Invasion. Hiyami presumably assists her teammates until the attack is repelled.

Round Six
Ninomiya Squad fights against Kageura Squad, Azuma Squad and Suzunari First in the night division of the sixth round of rank battles. Kageura Squad and Ninomiya Squad tie at the top with three points. No Squad receives the survival bonus due to there being multiple survivors. Following the match, Kageura Squad remains in first place with a point total of 37.

Round Seven
Since Tamakoma Second faces off against Kageura Squad, Azuma Squad and Suzunari First in the day division of rank battles on March 1, it can be inferred that Ninomiya Squad competes against Ikoma Squad and Ōji Squad in the night division.

Round Eight
The following evening, the members of Ninomiya Squad run into Chika, Osamu Mikumo, Kirie Konami and Shiori Usami at a restaurant. Hiyami forbids Konami and Usami to mess with Tsuji before helping him remember what Haruaki Azuma's favorite dish is. When he claims that he was able to converse with Hatohara because she was nice from the start, Hiyami suspects that he is trying to imply that she was not. He states that she was guarded at first, but that she is kind now. When the conversation moves to Hatohara, she remembers that she left right after they went out for a barbecue. Her teammates and she finish their meal and leave before the Tamakoma members.

On March 5, Ninomiya Squad fights the last rank battle of the season against Tamakoma Second, Ikoma Squad and Yuba Squad. Hiyami warns Inukai, who is training with Tsuji, when the match is about to begin. When Chika and Yūma don a Bagworm, Hiyami suggests that they are attempting to escape, although they might also be planning an ambush. She then recommends Ninomiya and Tsuji also go off-radar to avoid Kazuto Tonooka. Chika eventually begins to bombard the remaining combatants, with Hiyami warning her teammates that more rounds are likely to follow. She enhances Inukai's vision so it will be easier for him to intercept the incoming explosives. The match ends in Tamakoma Second's victory, with Ninomiya Squad placing second. The three points garnered put their final score at 44, allowing them to retain their position as B-rank #1.