The main reason why the Japanese sit on the floor is a tradition. The Tatami Culture further reinforces this. Because they sit on the floor to eat (using tatami) and also use the floor to sleep (using the futon), they take their shoes off to keep the space clean and avoid any making the floor filthy. The shoes are taken off in the Genkan (the entrance of the house or apartment) and are often replaced with Uwabaki (slippers).