Sakuno is Shingo's younger stepsister and first-year student of Kagamidai Academy; her father remarried Shingo's mother about ten years ago. She has a quiet personality and is good at cooking, but has a poor sense of direction and often gets lost. She was selected as a test student with her brother, and transferred to Yuihime Girls' Academy to participate in 1-T, the first-year test class. She happened to meet Airi at night on September 30, the day before the transferring on October 1. She became close friends with Airi at that time. She often goes shopping to Kume Mart, too. She is youngest but tallest among the main female characters.