A Magic School Full of Hidden Doors

In a certain place, there was a child named Shirayuki Aoi who was about to become a middle school student in April. That child had no memory of her biological mother from long ago. However, through her foster parent Shirayuki Masa, she came to visit her biological mother. "Shirayuki Aoi. You are the older twin sister, and you are a witch." She was told something she couldn't understand. Following what she was told, she ended up enrolling in a magic school with a child named Shirayuki Akane.