A car accident had erased Cheng Xiao's memory... would she still be able to remember what Eunseo had promised her? ------------------------FLASHBACK STARTS------------------------ "Please don't cry... i promise i will be back in 5 years , just 5 years... under the same sky... at the same time... in the same place..."  Its 12am in the morning... the start of 2017 Christmas when Eunseo last seen Cheng Xiao... -------------------------FLASHBACK ENDS---------------