The 11-year-old brother Chan Yi (played by Yu Seung-ho) actually takes care of his sister Xiao Yi (played by Jin Xiangqi) like an adult. The brother and sister have always believed that as long as they are obedient, one day their mother who ran away from home will come back to them. Xiao Yi's birthday is coming. In order to fulfill her wish, her brother gave her a newborn puppy. Xiao Yi thought it was a gift from her mother, so she named it "Xin Yi". With the company of "Xin Yi", Xiao Yi has a playmate when Chan Yi is not at home. The three little guys live happily like a family. In the blink of an eye, "Xinyi" grew up. On a sunny winter day, "Xinyi" pulled an ice sled and took Xiaoyi to play happily on the frozen river. Unexpectedly, an accident happened and Xiaoyi fell into an ice hole... Chanyi blamed "Xinyi" for Xiaoyi's accident. Without a mother and a sister named Xiaoyi, Chanyi could not accept "Xinyi" staying with him anymore, so Chanyi left home and started a new life, and "Xinyi" followed him and began a journey of pursuit...