The Legend of Zelda: Tri Force Heroes allows for as many as three playable characters, but they are all men because that's the way Nintendo designed the story, said game director Hiromasa Shikata in an interview with IGN.
Tri Force Heroes is a multiplayer game featuring three different versions of Link — one in his traditional green tunic, the others in red and blue. Up to three players can step into the boots of those Links and explore dungeons cooperatively. The setup is similar to The Legend of Zelda: Four Swords and The Legend of Zelda: Four Swords Adventures on the Game Boy Advance and GameCube, respectively.
Asked by IGN at E3 why it isn't possible to play as a woman in Tri Force Heroes, Shikata offered some background on the game's story in an attempt to explain. Shikata told IGN that the story begins with an event after which the ruler of a kingdom calls for heroes, and Link is one of the people who throws his cap into the ring.
"The story calls for this sort of legend/prophecy where heroes will come together to help solve a problem," said Shikata. "And in that, they are male characters. So, because the game is set with that as the story background, you cannot choose a gender; you are a male character."
IGN pressed Shikata on this point, pointing out that Tri Force Heroes offers multiple outfits that confer unique abilities — including the Legendary Dress worn by Zelda herself.
"I understand what you're saying, and just as general information, we do have a lot of female staff members who are playing this game and enjoying it," Shikata replied. "It doesn't seem to be a big issue to them. They still are getting emotional investment in this game." Shikata added that women can feel comfortable playing as Link in Tri Force Heroes because he "isn't the most masculine of guys in the world."
Shikata told Polygon at E3 that he hoped the ability for players to put Link in Zelda's dress would "broaden that appeal to some of our younger female gamers as well."
The Legend of Zelda: Tri Force Heroes will be available on Nintendo 3DS this fall.