The authors have previously shown that, by using shadow media that transforms the color and shapes of shadows to transform the relationship between individuals and shadow media, a variety of bodily expressions is created from individual performers. In this study, we attempted to support co-creative expressions by transforming the relationships between performers and shadow media space. Specifically, we developed shadow media utilizing point clouds (dappled shadows) and made it possible to freely alter the light source position of shadow media. In addition, we implemented a shadow media system that displays a shadow agent moving according to the movements of a group of performers (a virtual light source robot) on a stage, and used its position as a light source. As a result, we found that the expression space of performers expanded in comparison with existing shadow media systems. This result shows the possibility that this system supports the emergence of co-creative expressions.