This fearless fighter belongs to the Society, an organization which hunts primal beasts.  She has formed a contract with the seal weapon known as the Spear of Arvess.
She and her partner Vaseraga are charged by the Society with a variety of missions.  Though the two often butt heads, each has the other's complete trust.  Perhaps it is the contrast between Zeta's upbeat but stubborn personality and Vaseraga's unshakable calm which makes them such good partners.
In addition to the fierce mid-range spear attacks which keep her enemies at a distance, Zeta also has a talent for lightning-quick aerial combat.