Kazuyoshi Usui

Switch is the brains and secretary of the Sket Dan. As a result of the events that happened in his life, he opts to speak through a voice synthesizer on his computer. He has a deadpan sense of humor and seems to enjoy teasing others. Because he always communicates through speech synthesis software and has a tendency to joke with a straight face, it is difficult to tell what he is really thinking. While he usually "speaks" without much emotion, he would sometimes purposely raise his "voice" to abnormally high levels for comic relief. He often becomes very passionate about anime and often provides a very detailed and hilariously in depth commentary on the various anime featured in the series. He also has a strong belief in Science which is shown through his rivalry against Occult lover, Reiko Yuuki. The reason he doesn't talk is quite possibly because of the psychological damage he developed from his belief of something he said being the cause of his younger brother's death (Source: SKET Dance Wiki)