Cookie has warm gray hair and yellow eyes. She wears a gray one piece with short blue sleeves. Her ears are large and rounded, like most mice, and a long, prehensile tail. She has a short, gray cape. Her shoes are dark gray and her socks are light pink. She carries two crowbars around with her that can turn into flails. Around her neck is a pendant with a crystal shaped like a heart. Her left ear has two earrings.
She is a fun-loving and hyper girl. Cookie likes playing around and is very social. Her childish personality can cause her to be forgetful, but she tries to do her job to the best of her ability, so she is very loyal. She is very curious and can get herself into trouble at times, and she is also very mischievous, but can find her way out of problems easily. Most of the time, Cookie is dependable and honest, but her childish personality can get in the way.
She resides at the Tadase Temple with her colleagues. She is learning how to become a priest there, along with her friend and her boss. Cookie gets along easily with the creator of the temple, Mitsu, because she had given Cookie her weapon and protected her from the humans who wanted her dead. Cookie likes to venture outside of the temple on occasion, mostly to collect treasures to sell for funding so the temple can continue to run and has enough funds for buying weapons to protect themselves.