Kōji Oki/Plot

Background
Oki hails from Ōsaka, where he was scouted by Border.

Introduction Arc
Ikoma Unit presumably takes part in the extermination of all Rads in Mikado City.

Large-Scale Invasion Arc
Ikoma Unit is seemingly not deployed during the Second Large-Scale Invasion, and could therefore be among the B-rank units with missing members which Masafumi Shinoda prevents from fighting against Aftokrator's forces out of fear of capture.

Round Two
On February 5, Ikoma Unit faces off against Ninomiya Unit in the second round of rank battles. Since Azuma Unit, Katori Unit, Ōji Unit and Yuba Unit compete in a four-way match in the day division, it can be inferred that the three-way battle takes place in the night division and that Kageura Unit is the third participant.

Round Four
Since Tamakoma Second fights Ninomiya Unit, Kageura Unit and Azuma Unit in the night division of rank battles on February 15, and since Katori Unit and all other possible opponents were in the middle tier of B-rank or lower, Ikoma Unit must have fought in the day division against Ōji Unit and Yuba Unit. After the scores from both divisions are tallied, Ikoma Unit remains in third place.

Galopoula's Blitz
Since Azuma Unit, Kageura Unit and Yuba Unit fight in the night division of rank battles on February 19, Ikoma Unit must have competed in the day division against Ninomiya Unit, Ōji Unit and Suzunari First. They rank third at the end of the match. That same night, Ōji Unit and Ikoma Unit are deployed to intercept opponents west and south of the base in preparation of Galopoula's incursion.

Round Five (Night)
After the results of both the day and night divisions are tallied in round five, Ikoma Unit ranks third, with 27 points.

Round Six
Ikoma Unit is pitted against Ōji Unit and Tamakoma Second in round six. On the day of the match, the team members are gathered in the strategy room, discussing Tamakoma Second's prowess. When Tatsuhito Ikoma suggests keeping an eye on Chika Amatori because she is cute, Oki infers from Maori Hosoi's expression that she is thinking about the fact that her captain, who always praises other girls' appearance, has never done so with her, prompting the other guys in the unit to compliment her. Satoshi Mizukami tasks him with taking out Chika once she reveals her position, which he agrees to do. The conversation moves to the menu of the cafeteria until the start of the match.

Oki spawns to the south-west of Cityscape A, near the center. He climbs to the top of a building with Grasshopper and is immediately spotted by Yutaka Kashio. He takes a shot at the Attacker, who withdraws, to Oki's surprise. The Sniper moves westward, and objects to Ikoma saying that he is popular. When Mizukami and Ikoma force Kazuki Kurauchi to leap above the roofs, Oki takes a shot at him, injuring his shoulder. Chika also opens fire, so Hosoi sends her coordinates to Oki. He shares his resentment about having to shoot at a young girl and remarks that he will find it difficult, although his teammates do not believe him. He suggests swapping targets with Ikoma, who replies that Oki is the only one handsome enough to be able to afford taking out young girls. However, he is soon spotted by Kazuaki Ōji and forced to flee with Grasshopper. Mizukami urges him to survive until Ikoma and he move their fight against Yūma Kuga closer to him. Ōji soon stops giving chase, so Oki assists his teammates, but only manages to shoot off Yūma's arm.

Chika reaches a position from which she can begin to destroy possible hiding places for Ikoma and Mizukami. Oki attempts to snipe her, but she blocks with an unfocused Shield, leading him to realize that he has to shoot immediately after she opens fire. Since she knows his position, he is forced to move to a new location. His suppressive fire prevents her from assisting Yūma until she surprisingly appears to attempt a mutual kill. He is hit by her Lead Bullet while his shot severs her leg. Unable to flee, he fires at Yūma as he closes in, but is forced to bail out. The match ends moments afterwards with Ikoma Unit and Ōji Unit scoring three points against Tamakoma Second's four. After the results from both the day and night division are tallied, Ikoma Unit remains in third place with a point total of 34.

Round Seven
Oki approaches Chika at the end of a Radar search drill. Isami Tōma teases him about getting cold feet at the end of round six, to which Oki responds that Chika made him think about the younger sister he always wanted and that he could not shoot someone as cute as her, incurring Yuzuru Ema's jealousy. Akane Hiura asks him if he would have trouble sniping her too, which he confirms.

Since Tamakoma Second faces off against Kageura Unit, Azuma Unit and Suzunari First in the day division of rank battles on March 1, it can be inferred that Ikoma Unit competes against Ōji Unit and Ninomiya Unit in the night division. After the results of both the day and night divisions are tallied, Ikoma Unit ranks fourth.

Round Eight
On March 5, Ikoma Unit is pitted against Ninomiya Unit, Tamakoma Second and Yuba Unit in the night division of rank battles. Shortly before the match, Oki equips Ibis to deal with Hyuse. The fighters are as relaxed as ever, listening to Ikoma's rambling stories. A worried Hosoi asks Oki if he shouldn't target Chika to counter her Meteor.

Oki spawns in the center-east of Cityscape B. After bounding atop a building, he spots Takuma Yuba and Yukari Obishima, who have already met up, in the north, and warns Kai Minamisawa that they might be coming after him. His attention is temporarily diverted by Masataka Ninomiya's bombardment. He then spots Hyuse just as he goes off-Radar and proceeds to head south. Oki moves towards Ikoma as he forces Hyuse into the air with an Ikoma Senkū. Oki fires at Hyuse with Ibis, but the Tamakoma Second ace blocks with Full Guard, having anticipated the addition to Oki's arsenal. As Ikoma Unit and Yuba Unit begin to focus on Hyuse, Oki tells his captain not to clutter their comms with useless recaps. Shortly afterwards, Chike prepares to launch her Meteor at the cluster of enemies, but it detonates before she can fire it. Oki apprizes his teammates and intuits that Kazuto Tonooka is behind the premature explosion and, since the other fighters are wary of being sniped and the Sniper's aptitude at stealth makes him dangerous if he disappears, Oki switches to targeting him.

His chance comes after Chika lures Tonooka's shot and fires Hound at him. He leaps down a building to avoid the homing bullets, only to be sniped in mid-air by Oki. Mizukami complains about him not using those skills to help them, but he objects that there were no openings. He warns Minamisawa that Yūma is headed his way and tells him to lure Obishima in his direction, but before he can begin to move towards his teammate, he sees what appear to be Hound bullets coming towards him; however, after his first evasive maneuver fails he realizes that Ninomiya is using Hornet. He narrowly survives the attack, only to be cut down by a Bagworm-wearing Shinnosuke Tsuji, to his astoundment.

The match terminates with Ikoma Unit and Yuba Unit tied in third place, having scored two points each. The season of rank battles ends with Ikoma Unit ranking fourth, with a total of 34 points.