The Chunichi Dragons announced today that Dayan Viciedo returned to the United States earlier in the day. Viciedo is in the process of acquiring US citizenship. He is expected to return as soon as everything is complete (he missed parts of the season last year for the same reason, but was unable to finalize the process).
[UPDATE 4/28 @ 2:14am]
Viciedo returned to Japan on April 27. He will join Ni-gun practices on April 28.