Fyana originated as Proto-One, the first genetically engineered Melkian Perfect Soldier. Special substances suppressed her emotions while enhancing combat instincts, creating a deadly living weapon. Her first encounter with Chirico Cuvie during a mission led to her abandonment after the Perfect Soldier program's cancellation. Incomplete modifications meant she lacked the full capabilities of later models. She later emerged as the enigmatic Phantom Lady in Udo City before Chirico named her Fyana, initiating her emotional development and journey toward humanity.

Her relationship with Chirico, described as Birds of a Feather, became central to her evolution. This bond fueled mutual transformation: Chirico's stoicism softened through her influence, while she gained genuine emotions and autonomy. This dynamic faced significant tests during the Kummen and Sunsa arcs, where she fought alongside Chirico, offering tactical support and piloting Armored Troopers in combat. Her presence consistently countered his vengeful impulses, preventing indiscriminate violence.

Later OVAs, particularly *Shining Heresy*, substantially contracted Fyana's role. Separated from Chirico during a sudden cryosleep awakening, she was largely incapacitated. The narrative focus shifted to Chirico and a new character, Teitania, a Nextant successor to the Perfect Soldiers, leaving Fyana passive and underutilized. Her reduced agency culminated in an ambiguous fate, leaving her character arc unresolved.

Fyana's initial story concluded in the original TV series with her entering cryosleep alongside Chirico, awaiting peace. Subsequent OVAs disrupted this resolution, reframing her primarily as a motivator for Chirico's actions rather than an independently developed character.