Vanishing Time: A Boy Who Returned (2016)

Soo Rin, a schoolgirl, has moved house because of her stepfather’s job. At her new school, people label her as a weirdo and shun her after reading her blog. However, Sung Min, from the year above her, befriends her and they fall in love. One day, Soo Rin’s friends – Sung Min, Sung Min 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 realises that the boys have disappeared, and the police begin searching for them. A few days later, Sung Min reappears, but as an adult.