Yume is the student of Kazemi affiliated junior high class 2-1. She is Otome's younger sister, and one of Jun'ichi and Nemu's granddaughters. Her first name literally means "dream." Due to her magician blood, she sees the future in her dreams. In the first season of the anime, Yume's accommodating personality is being portrayed when she easily became friends with Minatsu. Yume is also there to support Minatsu in times of trouble and also show signs of defensiveness towards Minatsu when others found out about the latter being a robot. In the second season of the anime, Yume is depicted to be rather lonely after Minatsu leaves the school.
Source from Wikipeida