Since his parents died knocked down by a mad bull, Mugifume Yamano, 21, is the only policeman in Ton-Ton village. He is assisted in his task by his younger sister and brother, Takenoko (4 years old) and Kurimaru (1 and a half). Mugifume moves by bicycle and, unfortunately, he is very naive, clumsy, and extremely stupid. One day, he meets the tiny Chii, a humanoid alien girl who came form planet Micron in a flying teapot. Chii has magical powers that will allow Mugifumie solve the problems in town more easily.

(Source: Dragon Ball Wiki)

Note: The first chapter of Chobit is made up of 3 sub-chapters, increasing the chapter count from 2 to 4.