Mari has been living with her grandmother for the past 5 years after a tragedy caused the loss of her home, family, and her memories. Fearing for her future, her grandmother admits her into Kaihou Academy to give her a chance for a normal childhood. Once there she meets Hagino. At first Hagino appears like a normal student, but inside her lies a deep secret that relates to Mari's tragedy. Uncover the mysteries in Blue Drop!