Kiyoshi Kurosawa, in his films, often talks about the coexistence of what is and what is not in everyday. He also deals with the coexistence of what is believed not to be and what is forgotten just like life and death as well as transcendental power. In his films, however, when characters are suddenly faced with the existence which is believed not to be or forgotten, they get confused but also find the other sides of themselves. As the title indicates, this film Doppelganger is a story of a man who meets his other self. One day, Hayasaki who is developing a robot chair for the disabled and patients, meets his other self who is more violent but much freer than himself. So sometimes, Hayasaki feels released when his other self frustrates his plans against his intention. That means nothing but the spurt of his desire that has been suppressed within a social or moral rule. Through that odd coexistence, Hayasaki begins to find out the other side of himself which he never realized before. Then, who on earth is that Hayasaki who survived at the last scene? Kiyoshi Kurosawa began Doppelganger as a thriller film but ends it with a philosophic question about ′the nature of human beings′.