The Whistle (2003)

Original title: คู่แท้ปาฏิหาริย์

As if by magic, Nam meets her elementary school friend when her life is in danger. After that encounter, Muton keeps appearing when Nam is most in need and always helps her through whatever difficulty she is facing. One day, when Nam and Muton realizes that Nam has heart disease, they decide to spend her last moments together as each has realized that they are deeply in love. During their vacation on the beach one day, Muton suddenly feels a serious pain in his chest and vanishes into thin air. Nam does not know what to make of it but is determine to solve the mystery behind her lover's disappearance. What she finds will both break and save her heart.