The Japanese term for mobile phone, keitai (roughly translated as "something you carry with you"), evokes not technical capability or freedom of movement but intimacy and portability, defining a personal accessory that allows constant social connection. Japan's enthusiastic engagement with mobile technology has become -- along with anime, manga, and sushi -- part of its trendsetting popular culture. Personal, Portable, Pedestrian, the first book-length English-language treatment of mobile communication use in Japan, covers the transformation of keitai from business tool to personal device for communication and play.