Jieum hears the news that Seungjo, whom she has harbor-longingly crushed on since high school, has a girlfriend. Wanting to pour out her wounded heart somewhere, she stumbles upon a chatting app called <Thumping Planet>, where she meets 'Jemulpo Puppy' and has a brief escape from reality. Then, after winter break, she returns to school for the new semester. 'Wait, wait a minute. Why is that person here?!' There, she comes face to face with 'Jemulpo Puppy', whom she thought she would never see again... "Found you, little pebble."