The Giants are apparently working out the mystery man at their ni-gun facility. The reports don't give his name, but there are a few hints: Sponichi and Nikkan Sports both say that he's a switch-hitting catcher, Sponichi says his Dominican, while Nikkan suggests he could be from another Latin American country, and adds that he's 20-15 years old, not currently with any team, and that the name "Noel" was written on the batting practice list. A quick search for :Noel" at baseballreference.com doesn't return any likely matches.
The tryout runs through the 28th, so we'll have to wait until tomorrow to find out the mystery player's identity.