So after watching all 4 episodes :
- Lee Hyunjin is a spy for Lee Know as he vowed to do that for the sake of his (alleged) hyung
- Their main goal is to take over the STAY Company from Yang Jeongin
- Yang Jeongin, on the other hand, is on the mission to search for his long lost brother, Yang Hunjin
- While on the mission Hyunjin found the things regarding missing person called Yang Hunjin and his tears came out of nowhere
- Lee Know sensed that Hyunjin is about to know the truth and remembered 12 years ago incident that made him vowed to destroy Yang Jeongin, because Yang Jeongin took the very last pudding left in the cafe
- Hyunjin sneezed SKZ and that's when Jeongin realised he is the hyung he has been searching for
Its sooo😭😭😭😭😭