Kō Murakami/Plot

Background
Throughout his life, Murakami has suffered isolation due to his Side Effect: his friends would teach him new games and sports, only for him to rapidly become unbeatable, alienating his friends from the activities they had introduced him to and causing the group dynamics to fall apart. For this reason, he developed a negative view of his Side Effect, which he perceived as forcing him to steal others' hard work.

Murakami was scouted by Border from outside the prefecture[BBF Q130] and ended up joining the organization approximately one year before Chika Amatori and Yūma Kuga. When asked what position he would like to cover, he made himself available for and and all of them, so he was assigned to the newly created Suzunari Branch.[BBF Q84] He became training as an Attacker under Tetsuji Arafune, whom he surpassed in a little over six months. Around that same time, Arafune reached Master Class as an Attacker and switched to Sniper, and the rumor began to spread that he had swapped classes because of Murakami, which resulted in the latter falling into a slump. After Tatsuya Kuruma speaks with Arafune, however, Murakami learns the truth behind his former teacher's change, and with Kuruma's encouragement he manages to overcome his complex about his Side Effect. Nonetheless, the rumor lingers around eight months since the fact. After that moment, Murakami began to spar against some of Border's most powerful agents, learning a great deal from each one of them thanks to his Side Effect.

Introduction Arc
Suzunari First was presumably involved in the extermination of all Rads in Mikado City.

Large-Scale Invasion Arc
Suzunari First is deployed by Masafumi Shinoda to prevent the initial wave of Trion Warriors sent by Aftokrator from reaching Mikado City. Border's traps buy them enough time to arrive on the scene. When a Rabbit emerges from a carcass, Murakami tells an intimidated Kuruma to step back. Suzunari First attempts to meet up with Haruaki Azuma, but the Rabbit continues chasing them, until Murakami volunteers to take it on by himself while his teammates meet up with the other B-ranks. He manages to hold back the Trion Warrior, but two more join it. Murakami loses an arm in the ensuing confrontation, but resolves to continue delaying them for as long as he can, until Kei Tachikawa arrives and quickly dispatches them. He tells Yuu Kunichika to give two of the kills to Murakami, as he had damaged them the most. Murakami apprizes the no. 1 Attacker of the Black Trigger user who defeated Sōya Kazama and the ongoing confrontation between a group of B-ranks and another humanoid Neighbor.

After the end of the invasion, Suzunari First becomes the recipient of an Excellent Distinguished Service award.

B-Rank Rank Battles Arc
On February 1, Suwa Unit manages to score a win against Suzunari First and force Murakami to bail out thanks to Kōtarō Suwa and Daichi Tsutsumi combining their firepower outside of the Attacker's range. Four days later, Suzunari First fights a rank battle against Nasu Unit, Urushima Unit and Kakizaki Unit, which results in Suzunari First's sixth consecutive victory against Nasu Unit.

On that same day Murakami visists the sparring hall, his presence sparking excited chatter. He immediately spots Arafune and the two chat until Murakami notices Yūma, having come to see Osamu Mikumo and him for their accomplishments against Arafune Unit. He asks Shun Midorikawa to spar with him, but due to his recent losses to Yūma, he is not in the mood for it, whereas the enthusiastic Yōsuke Yoneya is turned down on account of him not using Grasshopper. The ace of Tamakoma Second volunteers, despite the other Attackers attempting to dissuade him. Murakami agrees on the condition that they have a ten-round match, and that they take a 15-minute break halfway through. After the first five rounds Yūma is in the lead, but the tides turn when he loses all remaining rounds, leading to a score of 6-4 for Murakami. The no. 4 Attacker tells his opponent about his Side Effect.

The next day Murakami shares the news of his duel with Kuruma and Yuka Kon, claiming that not only Yūma will also learn from the experience, but that he might have been holding back, and recommends fighting him in the upcoming match only with the whole unit by his side. When Betsuyaku arrives, Murakami is amused by his antics. Two days later, on February 8, after the members of Suzunari First review their plans, they wait for Murakami to wake up. He spawns in the western area of Riverbank together with Yūko Kumagai and Akane Hiura. The four immediately start heading towards the bridge, which is however demolished by Chika before anyone can cross. Murakami prepares to engage Kumagai, who reached the bridge first.

Murakami promises his teammates to reach them at any cost once the opponents on his side of the river are dealt with. He clashes with Kumagai, narrowly avoiding being thrown into the river by Yūma. The Attackers begin a three-way fight. Murakami's concern fo rhis teammates causes him to break the stalemate with a more forceful attempt to take out Yūma, but the ace of Tamakoma Second exploits it to lure Hiura into shooting and rushes to pick her off, leaving Kumagai by herself against Murakami. Fearing that Yūma will cross the bridge, the two move back towards it. Murakami quickly cuts off Kumagai's arm, which prompts her to fight back with Meteor. However, Murakami manages to get her to self-destruct, and avoids the trap she left behind. His attempts to bait Yūma into attacking are unsuccessful, but the opponent unexpectedly decides to face him instead of crossing over to the other bank. As the two clash, Murakami rapidly geains the edge by seeing through all of Yūma's techniques thanks to the experience gathered through his Side Effect.

Yūma tries to outmaneuver Murakami with Grasshopper, to no avail, so he lures him to the bridge, where he has the Suzunari First ace stop on one of the repelling pads, launching him up in the air. Between Yūma giving chase and Chika blowing up what was left of a nearby support pillar, Murakami is unable to escape. Both Attackers fall into the river, where Yūma uses Scorpion's versatility to defeat Murakami. After the battle is over, the no. 4 Attacker apologizes to Kuruma and convenes with Tachikawa's commentary.

Following the Round 3 battle, Murakami and Yūma forge a friendly rivalry, competing in solo rank battles in their free time. After another of Murakami's triumphs, he proposes to introduce Yūma to Masato Kageura, against whose unit Tamakoma Second will soon clash. He introduces him as one of four Attackers he has more losses than wins against, and gives Yūma an overview of Kageura Unit. When Yūma asks why Kageura is ranked only 20th if he is stronger than Murakami, the latter responds that he will see it for himself. The two see him in the solo rank battles hall moments before he beheads two trainees. Murakami warns Yūma not to stare too hard lest Kageura snap at him too. After the two greet each other, the two trainees complain about Kageura's actions to Murakami, who assures them that their aggressor would not harm them in their flesh and blood body and sets them running by telling them that Kageura can read minds, which Yūma picks up as a lie. Murakami and Kageura discuss the incident for a few moments before Yūma steps in. The notion of the short, younger-looking boy defeating Murakami amuses Kageura, who then proceeds to try to rile Yūma up in spite of Murakami's objection. Yūma's nonchalance surprises the other two Attackers, and Kageura decides to leave without sparring. At Yūma's request, Murakami explains him how Kageura's Side Effect works exactly, and remarks that he gets a similar vibe from the two of them.

Some time later, Kuruma and Murakami begin to work on a new formation which greatly increases their firepower at mid-range, rapidly making it combat-worthy through a mixture of practice and Murakami's Side Effect.

On the night of Galopoula's blitz, Murakami is stationed to defend the expedition ship together with Tachikawa, Kazama and Konami. He is shocked to hear that according to Yūichi Jin's foresight, Tachikawa will be split in two. Shortly afterwards Gatlin and Ratarikov arrive, and only Murakami's timely intervention prevents them from instantly destroying the away ship. A Dog curs off Murakami's arm, but it is quickly dispatched by Konami. When the two parties clash, Murakami remains in position in front of the hanger, ready for the next shot. He throws his Raygust at Ratarikov, who deflects it. Kazama then tasks him, Konami and Tachikawa with taking down Gatlin. Always standing between him and the ship, when Gatlin comes close enough Murakami combines his strength with the other two Attackers', but the enemy commander manages to survive the offensive unscathed.

With the cannon ready for the next shot, Ratarikov and the Dogs put more pressure on Murakami, whose loss of an arm prevents him from effectively fighting back. When Gatlin pins down Tachikawa right in front of himself, Murakami fears that he will not be able to stop the next blast, as his view is blocked; however, Konami bisecting both Gatlin and Tachikawa gives Murakami a direct line of sight and enough time to neutralize Gatlin's final shot before he bails out. Kazama apologizes to Murakami for letting some of Ratarikov's attacks through, but the ace replies that Kazama did plenty. The four Attackers continue guarding the hangar until the end of the blitz.

On February 23 Kageura, Murakami and Yūma spar together before hanging out with Yuzuru Ema, Hiro Kitazoe and Isami Tōma at Kageura's family's restaurant, where they are later reached by Arafune and Atsushi Hokari. The matter of Ema's willingness to throw the next match is broached, and when Ema leaves Murakami is confident that he has changed his mind on the subject following everyone's interventions. He is surprised by Tōma's certainty that Chika, contrary to the table's belief, would be able to shoot someone else if she wanted to.

The members of Suzunari First gather to prepare a strategy three days before their match against Azuma Unit, Kageura Unit and Tamakoma Second on March 1, during which Kuruma and Murakami discuss the necessity of coming up with a new strategy apart from their latest formation. On the day of the match they are surprised by Tamakoma Second's addition of a new member at the last minute. Murakami responds to Kon's question and Betsuyaku's optimism with balanced opinions, and together with the Operator he urges Kuruma not to change the map they previously agreed upon: Cityscape D. Kuruma then proceeds to review the strategy one last time before transmission is initiated.

Murakami spawns on the third floor of the mall, one floor below Kitazoe. The two quickly spot each other and Kitazoe opens fire, but Murakami easily pulls back to safety. He reports the encounter to Kuruma, speculating that Kitazoe is heading up to meet with Kageura, before the two start to pursue him. The two captains reach their teammates simultaneously, and a firefight breaks out on the sixth floor between the Gunners of each team. The Attackers soon begin trading blows as well, with Murakami also covering for Kuruma. When Kitazoe threatens to overwhelm him, Kuruma switches into a Full Attack stance while Murakami focuses entirely on protecting him, turning the tables on their opponents.

Kageura and Kitazoe take shelter inside a restaurant, the narrow space preventing Kuruma from using his pincer attack, but just as they seem to be regaining the upper hand, Betsuyaku turns off the lights in the mall. Murakami's black Kogetsu becoems invisible in the darkness, but Kageura manaes to dodge it thanks to his Side Effect; however, not even the latter can save him from a slash synchronized with Betsuyaku turning the light back on while his visual support is active, and although he survives the attack, he is severely injured. Kitazoe shoots the light fixtures to prevent the opponents from replicating their plan, but Murakami insists on pressing on and taking out Kageura as soon as possible. Shortly after Betsuyaku bails out the two teams resume fighting outside of the restaurant. With Yūma and Hyuse's sudden arrival the three pairs take some distance as they observe each other. Kuruma and Murakami relocate across the atrium to open fire when Kageura Unit and Tamakoma Second will converge, but Hyuse's Escudo forestalls them. Kuruma and Murakami catch a glimpse of Hyuse's "Asteroid" and deduce that his fighting style is similar to an All-Rounder's. Both Kageura and Kitazoe bail out as a result of the exchange, the point for the former's defeat going to Suzunari First.

When Hyuse dispels the barriers, the two teams clash, with Murakami continuing to protect Kuruma while the latter blasts away at the opponents in Full Attack. Suzunari First gains the upper hand as Murakami cuts down Hyuse's Escudo while Kuruma whittles their Shields away, but the tides turn when Hyuse manages to close in on Murakami and cause an Escudo to burst out of Murakami's own body, pushing Kuruma towards a concealed Osamu. Putting Kuruma's safety above his own as always, Murakami throws his Raygust at Osamu and is caught in a pincer attack by Hyuse and Yūma. He retaliates by activating Senkū while executing a slash that severs Yūma's arm behind him and seems to put him in a prime position to cut down Hyuse as well, but Yūma kicks the shield protruding from his back, causing him to miss and leaving him open to Hyuse's fatal thrust. Murakami bails out. After the end of the match, he listens to the commentary with his teammates.