Until everything returns to its rightful place, I wanted to entrust my time to Hanseung.\n\nAfter receiving a C grade in Jisuyun's class and missing out on a scholarship, Hanseung reluctantly starts working part-time at the school library. They say enemies meet on a narrow bridge, but while wringing out a mop in the bathroom, Hanseung unexpectedly encounters Suyun. After a heated argument with Suyun, as Hanseung leaves the bathroom, a group of students approaches, referring to her as 'professor' and treating her as they would Suyun. Confused, Hanseung finally realizes that their clothes have been swapped. Not only that, but everything, including identification and family relations, has been exchanged with Suyun. Thus, the two of them begin to live each other's lives...