Multimedia technology in theatre is nothing new, but various companies in modern and post-modern Japan, such as Dumb Type, Hatsune Miku, and the robot theatre of Oriza Hirata and Hiroshi Ishiguro, have been experimenting with mediatized technology. This thesis hones in on these Japanese multimedia theatres. It studies the origins of mediatization in theatre, looking at the impact of the innovations made by Adolphe Appia. Furthermore, the growing impact of media technology can create a perception of ‘Liveness’ of these artificial actors. Liveness is a critically important concept, both on and off stage, affecting how one perceives the non-human and the type of relationships that are conveyed between the human and non-human actor, as well as the non-human actor and its human audience. This thesis covers the productions of “A One Woman Show” and a spoiler-heavy discussion on "Super Danganronpa 2 The Stage ~Sayonara Zetsubō Gakuen~" within the context of the impact of projections on stage. Robots and the uncanny valley are also reviewed, with the play "Sayonara" as the primary case study within this topic. Then the thesis analyzes the experimental human theatre of Dumb Type, focusing on their plays "S/N" and "pH," as well Vocaloid concerts and the impact of these characters, especially Hatsune Miku, upon the fans. In the course of this analysis, reasons are suggested as to why these technological innovations have found particular success in Japan. / Graduate