Love them for you (hyunho)

Just a college group of four friends with normal life's, or so the three of them thought. They were just chilling little before the summer break , untill one of them suddenly disappeared. The other three did everything in their power to find him , but it was useless. It's like he never existed , there was no trace of him. It was their worst summer ,but is it?? Eventually the new school year began and the three of them meet four younger boys who have just joined their school. They were all an year younger than them , but they became friend really fast. Soon enough, the younger four found out about the elders' missing friend. But did all of them just found out or did one or more of them already knows about it??