<qa>  What is the daily urine volume of OPC-41061?This is a study to investigate the efficacy and safety of OPC-41061 by 24-week oral administration of OPC-41061 at 15-mg or 30-mg or placebo in patients with chronic renal failure who are undergoing hemodialysis or hemodiafiltration and who have daily urine volume of at least 500 mLday. 