Saki Mizukoshi(水越 紗季 Mizukoshi Saki?) is Natsumi's best friend and next door neighbour who is transfering schools due to her parents moving to Tokyo because they got promoted.She did not tell any of her friends which made Natsumi mad at her.She doesn't tend to believe supernatural things.She has dreamed of entering the tennis championship with Natsumi.Her parents work at the hospital.
She has long blond hair and brown eyes. She wears the school uniform. She is an only child. She gets mad easily and can be stubborn. She does not know how to speak for herself or talk about how she feels. But she will come when her friends need her the most. She is 14 years old.