Nowadays computers are considered a common tool for everyday activities, including document management and message communication. This in turn requests us to care- fully design computers so that anyone can use them without any special skill. Augmented/mixed reality and tangible in- terface would be promising toward the development of such daily use interface systems.

In this paper, we propose a new interface which is named O-Key. O-Key allows the user with his/her hands to scoop up objects which are virtually floating on the water in a bucket. A certain function associated with the selected ob- jects is activated. An experiment showed that the proposed interface works effectively. Possible application scenarios of the interface system are also presented.