When Seohyun was 7, she got caught in a car crash. That caused her serious injuries to the head resulting in memory loss. Krystal waits for Seohyun to come back after she mysteriously dissapeared. The day before they had gotten lost in a flower garden and an owner found them near a bed of forget-me-nots. She told them it meant pure and true love. Then the owner brought them back to their parents. That day Krystal and Seohyun promised to never forget each other. But now Seohyun comes back not