Alexia Lynn Elesius's younger sister in Wild Arms XF. Even though Alexia has gone missing, Katrina cannot inherit the Elesius kingdom for two reasons; her inability to communicate with Filgaia's Guardians, and her mental disorder where she cannot experience fear. The Elder Statesmen use her as a puppet ruler and damage her self-confidence. Despite her inability, they improperly perform traditional rites and ceremonies for Katrina to hear the Guardians.
Instead, a malevolent entity called the Clysmian of Fear enters her body and manifests over time with doses of terror that thrill Katrina. The Clysmian grows so strong that it wants to experience the world's terror at once, leading to the game's final battle - a battle that Katrina does not survive.