Installing a live camera in an office or laboratory can provide reliable high-quality communication among collaborators who are physically separated, but may also lead to privacy concerns. We propose a technique for displaying presence information using a three-dimensional object as a mask that covers the image of people in the live camera system. Our technique enables information to be shared partially, enabling sufficient communication while alleviating the discomfort of feeling monitored by the camera. The system also clarifies less-visible activities such as typing text using a keyboard or moving a mouse of people in the camera image. We implemented the Koka-ComeCam system using our proposed technique.