The thin man is a girl, very thin indeed. His small body hides extraordinary persistence and hard work. In order to catch up with the popular "fat man" Liang Zhiwen, he spent the best years of his youth in the summer solstice. If feelings could be weighed, it would definitely be 21 grams, because the soul that loves wholeheartedly is 21 grams. In the summer solstice, he used his 21 grams of soul to move the campus prince Liang Zhiwen. From high school to university, he went through the best years of his life.