Those assigned to TAK-385 will take a daily pill. Those assigned to degarelix will receive an injection under the skin once every four weeks at the clinic. They will start radiation therapy when testosterone is low enough, after at least 12 weeks of treatment. This trial will be conducted at clinics in the United States (US) and United Kingdom (UK). Participants will visit the clinic up to 14 times over 37 weeks for physical exams and blood tests, and might receive one follow-up telephone call.