Kota Fukuda is a member of the extermination squad that works under the Nozama Peston Service, a pest control company secretly tasked with hunting down and eliminating artificial life forms known as Amazons. He was originally an officer in the Metropolitan Police Department's Special Forces, where he served under his later squad leader Shido. Fukuda joined the extermination squad primarily to earn money for the care of his mother, who suffers from dementia. Quiet and reserved, Fukuda rarely shows emotion on his face and speaks little, yet he is deeply caring and loyal to his teammates. He was the first to show hesitation when a comrade was revealed to be an Amazon, he has shed tears for his fellow squad members, and he quietly offers support to those who join the team. His serious and professional exterior hides a warm and sensitive nature.

Fukuda's motivation shifts over the course of the story. Initially driven by the need to pay for his mother's medical treatment, he later becomes personally entangled in the conflict when his decision to let the young Amazon Mamoru go free leads to tragedy. Mamoru's actions indirectly cause Fukuda's mother to become infected with a new type of Amazon cell called lysogenic cells, which transforms humans into Amazons. Forced to put down his own mother with his own hands, Fukuda is consumed by regret. He blames himself not only for failing to kill Mamoru when he had the chance but also for failing to stop him from leaving. This loss hardens his resolve, and he acquires special crushing bullets designed to destroy tough Amazon targets. He then rejoins the reformed extermination squad to confront Mamoru and settle the matter once and for all.

Within the squad, Fukuda serves as the driver of the team's vehicle and as its primary sniper and rear support. He is exceptionally skilled with firearms, described as a crack shot capable of hitting almost any target, and his calm demeanor makes him a reliable asset during high-pressure operations. His relationship with Shido is the strongest of his connections, built on years of trust from their time together in the police force and carried into their work hunting Amazons. He also shares a quiet camaraderie with the other extermination squad members, including Takai, Misaki, and Haruka Mizusawa, the Amazon Omega Rider who briefly works alongside them. Through the losses he endures and the choices he makes, Fukuda develops from a mercenary driven by financial necessity into a man shaped by personal tragedy and a need for atonement. In the final confrontation depicted in The Last Judgement, he stands with his comrades to face the consequences of past decisions and to bring closure to the long conflict with Mamoru.