Five months have passed since Kyungsoo disappeared from his life. Since five months of that Kai continues to practice in order to become stronger. Until one day, after five months of not carrying out the mission, Kai gets a new mission with the same type, the mission to protect someone. Though Kai initially refused and did not want to protect others while Kyungsoo did not go back to him yet, but eventually he again received. Who will be protected by Kai this time? And if Kyung