The official Twitter account for the Mana series has tweeted a 10-second video of what looks to be Seiken Densetsu 3 being played on Switch.
Seiken Densetsu 3 originally launched for Super Famicom in Japan on September 30, 1995. It was never released in the west, nor has it ever showed up on the Wii, 3DS, or Wii U Virtual Console.
Square Enix has yet to officially announce a Switch version of Seiken Densetsu 3.
Watch the video below.
— 聖剣伝説 -公式- (@Seiken_PR) March 20, 2017