Cass is frantic and constantly panics when people tries to talk to her, however once you get you know her she calms down a bit. She's not used to many people since she often wants to be alone, which she talks about often. She hardly contributes to the group out of fear she'll say something wrong, but often helps ask important questions. Her voice actor should be able to be expressive with her. Again, accents are completely optional but will give you an edge if performed well. For reference, listen to Futaba Sakura from Persona 5

Pitch : Medium - high