Koume Sawaguchi hailed from Lower Tokyo, sporting orange hair, blue eyes, and blood type B. Her background included service in the Japan Ground Self-Defense Forces, where she earned the moniker "The Hurricane." Insubordination led to her discharge and forced transfer to the Terrestrial Administration Center, fueling lasting resentment toward her former commanding officer.

As the TAC's weapons specialist, she championed heavy artillery and the "bigger gun" philosophy, epitomized by her creed: "If you have bullets, keep shooting." She operated in a pink jumpsuit, projecting a brash, aggressive demeanor that defied traditional femininity. Beneath this toughness lay vulnerability, particularly in relationships and during high-stakes mission failures.

A pronounced superstitious streak saw her consulting astrological alignments for tactical choices. She frequently teased Yoshiki Yaegashi, the team's computer specialist, reflecting their contentious but shifting rapport. Initially dismissive of his skills, she grew to respect his resilience under extreme pressure, notably near the series' climax. This mutual dependence blossomed into romance, culminating in their engagement by the OVA sequel.

Contrasting her combat persona, she displayed softer instincts—befriending an abandoned puppy on patrol and actively encouraging romantic sparks between teammates Momiji Fujimiya and Mamoru Kusanagi. Her character arc involved confronting profound fears during the organization's gravest battles, where she vocalized terror yet persevered with Yaegashi's support.