Usas appears as a Persona of the Priestess Arcana. In Revelations: Persona, she was renamed as Chatz.
Digital Devil Saga: Avatar Tuner
Usas is the Atma Avatar of Jinana, leader of the Maribel. Serph, Argilla and Heat come face to face with Usas once Jinana has gone mad of hunger after refusing to eat others, even of other Tribes. In this state, which eventually all those who refuse to eat reach, she attacks everything in sight to sate her burning hunger. The Embryon are forced to kill her, as there is no recovering from this madness.
The battle against Usas is rather straightforward. She will use physical attacks, Hama, or try to inflict Charm status on party members. She has no weakness to take advantage of. After approximately half of her HP has been depleted she will begin to use Support to summon Unicorns to aid her. These can be ignored for the most part as they only pose a negligible threat. As long as a single Unicorn is present, Usas can use her Seraph Lore skill, however Void Expel will completely negate it. The battle will end as soon as Usas is defeated.
Digital Devil Saga: Avatar Tuner 2
Usas can be seen back to back with Prithivi when the latter uses the skill Seraph Lore, if she acquired it.