Krystal and Kai are couple. They are neighbour and not attend the same school. They had a secret plan that their partner didn't know about it. Krystal want to cheat behind Kai's back while Kai want to cheat behind her back. Both of them really didn't know about it. Because of their plan, one relationship disaster!! One love separated! One love vanished! Sehun and Jiyeon broke up because of their love game. Krystal likes Sehun and trie