Uda is, like Shinichi, a human who had a Parasite merge with a part of his body other than his brain. In Uda's case, the Parasite lodged in the lower part of his head. Uda's Parasite originally does not have a name, but is later renamed Jaw (ジョー, Jō?). It is brash and crude—it even seems to have a sense of humor—and sometimes assumes control of Uda's mouth, distorting it into odd shapes and forcing Uda to say strange or inappropriate things. The pair befriend Shinichi and Migi, but prefer to simply avoid Parasites. Because Uda is slightly overweight and his Parasite is located in the jaw area, fights with other Parasites tend to leave him out of breath. However, because it is located in the lower part of the head, his Parasite can extend itself downward into his chest, protecting his heart (a popular target in Parasite duels). Uda is normally a peaceful, easygoing man, but is nervous under pressure and cries easily. He works as a hotel employee.

(Source: Wikipedia)