Prologue

 Sixteen years old girl, Kairin Kashima is lying limply on the hospital bed with her head wrapped in bandages. A few days had passed since she is awake after she collapsed from falling down the stairs on her first day of high school. She hardly talk to anyone not even her own mother when she visited her. Doctors suspect that she may experience some retrograde amnesia because of her unresponsiveness. However, it is too early to confirm her condition as she could still be in shocked state from the impact.

 Every single day, a doctor called Ruiko Honda that acts as therapist would ask her some questions about her life as an effort to recover her lost memories. In the beginning, she is quite reluctant to answer the questions and occasionally pretends to sleep but slowly she is able to open up to Honda-sensei. Kairin knows that her name is Kairin Kashima, sixteen years old and live only with her mother. She also remembers about her likes and dislike, hobbies and what she want to be when she grow up yet she seems to forget about her childhood and people she met before the accident.
 One day, while on one of the usual therapy session, Kairin shows a tie clip as she mumbled slowly to Honda-sensei, "Sensei, who is the owner of this tie clip? Why do I have it with me? The nurse said I had it with me when I was sent in by ambulance"

 Honda smiles when she hears Kairin asked about that and replied kindly, "I'm afraid I can't answer it, Kairin-chan but only you can answer it if you try to remember it carefully"
 "Really?" Kairin asked again while clutching the tie clip tightly and looks into Honda face. She nods and pats Kairin's shoulder. "It must be really precious to you...but try to remember it little by little. Please don't force yourself too hard", Honda whispered. "I will," Kai replied with a bright smile for the first time ever.