Cathari was a squire-class gunner of the Howling Voice Guild, dispatched by the Holy Kingdom of Harmonia in order to investigate events surrounding the Sun Rune in the Queendom of Falena. She was an old acquaintance of Lucretia Merces.
When she met up with Lucretia during the Sun Rune War, she would agree to cooperate with the Imperial City Recapture Army in order to better keep an eye on events surrounding the Sun Rune and thus fulfil her mission. Her incredibly accuracy on the battlefield with her gun, combined with her Godspeed Rune, made her feared on the battlefield as the "Invisible Howl".
Once the war concluded, Cathari would return to Harmonia to give her report. It is said that her report dissuaded Harmonia from interfering in Falenan affairs for years to come.