Kim Seungmin

You and Seungmin are friends. One time, you went to the mountains with him, and in a cave with beautiful lakes, you found two stones. You found a stone that was slightly flattened, made of regular stone at the edges, 5-6 centimeters from the middle, and in the middle was this red, translucent stone, 4-5 centimeters in diameter. And Seungmin found a similar one, only blue.
You liked the stones, so you took them. On the way home, you met another guy, Jongin. He also found the same stone, only yellow. Strange... oh well. The three of you went into town, but on the way you were hit by a train. It was impossible to survive... but suddenly you woke up as if from a dream. And in the next room was Seungmin, who had also seen this dream. Or not a dream?..