Slow Loop: Koharu Minagi

 She became Hiyori’s stepsister after her dad and Hiyori’s mom remarried. She lost her mother and younger brother in a car accident when she was young. Koharu was born two months before Hiyori, making her the older sister (she likes to say that a lot). She had asthma as a child, so she couldn't go out much and was frequently hospitalized, so she spent a lot of time at home and didn't know much about playing outside.