Sunday is Derby Day in Japan, where Tokyo Racecourse hosts the Group 1, $3.48 million Tokyo Yushun, the Japan Derby. Danon Premium, unbeaten after four starts and already a Group 1 winner, is the solid antepost favorite despite the fact he has never raced beyond 2,000 meters and will be asked to negotiate 2,400 meters (about 1 1/2 miles) Sunday after missing his last intended start with a bruised hoof. Danon Premium’s connections say the Deep Impact colt has entirely recovered from the foot problem that forced him out of the April 15 Satsuki Sho, the Japanese 2,000 Guineas. Even so, Danon Premium will be racing for the first time Sunday since winning his 3-year-old debut March 4 in the Group 3 Hochi Hai Yayai Sho over 2,000 meters (about 1 1/4 miles) at Nakayama. In that start, Danon Premium pulled a good trip, stalking the pace and getting first run on the closers, including runner-up Wagnerian, who finished fastest and quickly galloped out. It might or might not be meaningful that Wagnerian returned to finish seventh in the Satsuki Sho. Danon Premium capped a 3-for-3 2-year-old season with an easy win over 1,600 meters at Hanshin in the Group 1 Asahi Hai Futurity Stakes, a race in which another Tokyo Yushun runner, the useful colt Stelvio, finished second. With Danon Premium out of the picture, Epoca d’Oro was a comfortable winner of the Satsuki Sho, a race in which three horses set a strong pace far in front of the rest of the field before coming back to the larger group of runners a little less than three furlongs from the finish. Epoca d’Oro traveled smoothly from fourth position, swooped up to the lead with about 200 meters left to race, and was easily best of 15 on the day. Blast Onepiece is relatively unproven, having never raced above the Group 3 level, but has won all three of his starts and was a course and distance winner this past February, one of the few in the field to already have tried 2,400 meters.