Tae-hoon and Mi-jung are both eighteen and in love. During winter break they go to the beach to celebrate their 100 days together as a couple. But once they come back from their trip, they are forced by their parents to never see each other until they become college students. Mi-jung begins to avoid Tae-hoon afterwards. And Tae-hoon begins to wander around Mi-jung. Winter turns to spring, and Tae-hoon and Mi-jung both turn nineteen.