Will You Be There (movie, 2016)

Soo-hyun comes across magical pills that allow him to go back and forth in time. 30 years to the past, young Soo-hyun meets future Soo-hyun and learns that his girlfriend will soon die because of him. In order to save her, the two Soo-hyuns try to change the past together, but a completely new and unexpected past is formed that leads to a new future.