Nani is a small alien that comes from another planet in a distant galaxy. He likes our planet and, as a kid, what he likes most is doing the things that children of Earth do. He is a very active and enterprising child, with a desire to do things and to learn.
Gugu is a small child who tries to discover what his alien friend wants to do each day. He always takes his wagon with him and, like any other children, he wants to do things to learn, to have fun, and to interact with his surroundings.