"Hide-and-seek" is a picture of two wild animals playing hide-and-seek in the metro station. An elephant hides behind the wall of the station hall. And the flamingo lurks behind a pillar in the down-track passage way of the station hall, looking out. The reason why the author choose them, is because they are the least likely two kinds of animals that could be associated with the metro space, as they come from Africa, which gives people a sense of maximizing unexpectedness. The entire metro space is like the game site for the two animals, bringing the feeling of smile and stimulating inspiration for passengers, and subconsciously enhance their sense of belonging and pride in the city.