Ubiquitous Virtual Reality, where ubiquitous computing meets mixed reality, is coming to our lives based on recent developments in the two fields. In this paper, we focus on the conceptual properties of contents including definition rather than infrastructures or algorithms for Ubiquitous Virtual Reality. For this purpose, we define u-Content and its descriptor with three conceptual key properties: u-Realism, u-Intelligence, and u-Mobility. Then we address the overall scheme of the descriptor with a Context-aware Augmented Reality Toolkit for visualization and management. We also show how the proposed concept is applied in the recent applications.