The tokens of love are all kinds of strange, they can be a leaf, a ring, or a love poem, but Su Cheng and Li An'an's token is just a song - Eason Chan's "Your Backpack". He sang it softly on the stage at the university New Year's Eve party and sang it into her heart. After everything that happened, An An never understood that their love was too shallow? Or is there no love at all?