Soobin and Yeonjun met in the school corridor, they bumped into each other and Yeonjun thought that Soobin was older because he was taller then. Yeonjun was his only friend. Soon, Yeonjun was diagnosed with an autoimmune disease. Yeonjun's parents were busy with their business and Yeonjun himself went to the doctors, but it didn't help, he was gradually dying. He was so weak that he could not simply walk without stopping. But he hid all his problems behind a smile.