A piece of youthful past, a song of sorrow for ten miles. Let's look at how yesterday the young man leaned on his horse and wore thin clothes, but now he is too lazy to look back. Looking back at the time, it seems as if it was yesterday, but the people around me are no longer there. The story of several teenagers. When they went down the mountain to experience, they were destined to be involved in this chaotic world. In the past, we knew each other and stayed together, but since then, we have forgotten each other across the world.