The Ephemeral Shadow is an interactive art installation centered on the concept of "simulacrum," focusing on the reconstruction of subjectivity at the intersection of reality and virtuality. Drawing inspiration from the aesthetic imagery of traditional shadow puppetry, the installation combines robotic performance and digital projection to create a multi-layered visual space, presenting a progressively dematerialized hyperreal experience. By blurring the audience's perception of the boundaries between entity and image, the work employs the replacement of physical presence with imagery as its core technique, critically reflecting on issues of technological subjectivity, affective computing, and ethics. Situated within the context of posthumanism and digital media, the installation prompts viewers to contemplate: as digital technologies increasingly approach and simulate "humanity," how can we reshape identity and perception while safeguarding the core values and ethical principles of human subjectivity?