Arc's Search for the Truth in the Witch Trial

My name is Serafina Ivanovna Petrova, you can also call me Arc. Now, I am trapped on an isolated island, together with 12 troubled girls, imprisoned by a weird owl called "The Warden". He claims that the reason for his imprisonment is that we carry witch factors, but is the truth really that simple? (This book is a fanfic of "Magical Girl: Witch Trial". You can watch it regardless of whether you know the original work. It is recommended to search for the illustrations to improve the sense of immersion. The murders in this book will be different from the original work, so I will take a long time to think about it.)