Admiral Mitsuya was a 24th century Starfleet flag officer. Mitsuya was one of the best poker players in the fleet, next to Jadzia Dax.
In mid-2370, Mitsuya diverted the USS Crockett to starbase Deep Space 9 to talk about Cardassian foreign policy. Dax claimed that that was just an excuse to get Commander Sisko in a game of poker because Mitsuya cleaned him out the year before. (DS9: "Paradise")
This character was only mentioned in dialogue.