Catherine is a demon shopkeeper, and twin sister of Alice. She is well-renowned for her clairvoyant abilities and mystical knowledge, but prefers collecting and maintaining strange curios and artifacts she comes across at her shop. Like Alice, she is rather calm, but instead of being mellow and sociable, she is sly and secretive. She intentionally keeps a mysterious persona, and is even a little on the greedy side. She's somewhat of a hustler and will not hesitate to extort shady figures, but only when she knows she can get away with it. She is definitely a bit of a troublemaker, though one with an overall good moral compass. She prefers to manipulate or jape those with malicious or otherwise bad intent. Along with clairvoyance, she can sense otherworldly forces, and she has the uncanny power to tell when someone is lying, although it is not entirely clear if the latter ability is entirely supernatural or if she is just incredibly good at reading body language. Though she has concentrated more of her magic on her psychic powers, she still has somewhat strong elemental magic, not really specializing in any one element but instead being a jack-of-all trades in this regard.

Catherine gets along well with her sister, but likes to tease her a lot. She knows she can be sensitive to this because Catherine was the "favorite child", so she tries to restrain herself sometimes, and knows when to quit. Unlike Alice, she took up her mother's trade of mysticism and trained her mental and supernatural abilities. Since Alice chose not to, their mother, Lorelei, is more outwardly showing of praise to Catherine. She enjoys the praise and wants to revel in it, but feels like this is unfair to Alice, even if she actually is more successful.

She has a friendly relationship with Carrie in the game, as her shop is nextdoor to Alice's pub, and Carrie delivers food to her. Catherine takes pleasure in mystifying her, and enjoys her innumerable questions about her. She is also in a secret relationship with Kyure. She is actually the one who initiated this, she initially sought out Kyure for his legendary reputation and incredible power, but soon fell in love with him and broke through his stalwart exterior. The reason this is kept a secret is because Kyure suspects that he will be perceived as weaker, or at least that his reputation of an unstoppable, unphasable force of reckoning would be weakened. Catherine realizes this is because he still doesn't know how people act very well, and even because he might be a bit insecure, and tries to convince him that love gives you strength rather than taking it away. Eventually she will also convince him that no intelligent person would dare cross or doubt Kyure's abilities and expect to live.