Soo Rin, a 6th grade student, moved due to her stepfather's job. In her new school, people label her as a weirdo and avoid her after reading her blog. However, Sung , from the next class, befriends her and they fall in love. One day, Soo Rin, Sung , and Sung 's friends Tae Shik and Jae Wook go to the mountains. There they find a cave under a tree which leads them to a mysterious egg. Soo Rin then notices that the boys have disappeared and the police start looking for them. A few days later, Sung appears again but as an adult.