The direct and active use of explosively evolved information technology in our physical daily lives can realize many advanced information services, contributing to the qualitative improvement of our individual life and, as an extension, our entire society. In such services with the active interaction between cyber and physical spaces, integrated systems consisting of numerous integrated circuits always exist as a physical entity at the boundary between the two spaces. In this paper, the required interface functionalities for the integrated system as the physical entity gateway connecting the boundaries are reviewed, and the physical shape of the efficient integrated system to realize these functionalities is determined. The direction of future research on such an interfacing integrated system is also discussed.