There are many fan theories about this character; the most popular around the game's release was that she was a brainwashed Jun Kazama, controlled by the lupine spirit that floated above her, although she only slightly resembles Jun (but always starts the match using her moveset). Nevertheless, as her name suggests, not much is known about her. She is the final boss character in TTT. A video leak revealed that she returns as the boss of the sequel and reveals that, yes, she is a possessed Jun.

Tropes associated with Unknown:

• Body Paint: The purple ooze that covers her body seems to be embedded in her skin. Without it, she'd be naked.
  • From some of the continue screens, it seems that her ooze, uh, oozes in and out of the skin.
• Brainwashed and Crazy: Certainly the case in the first Tag. The second title drops the "brainwashed" part and amps up the crazy.
• Demonic Possession: She breaks free of it in her ending, though.
  • In TTT2 if you lost to her it will go to a first person view of her standing over you. As the continue timer counts down she reaches her hand out and if it hits zero she reaches out to you, and the screen goes black. Jun has gone Darker and Edgier? Yeah looks like it.
• Ditto Fighter: Unlike other examples, she doesn't even need to wait until the end of the round.
  • No longer the case in TTT2, as Unknown uses only Jun's style with the added ability to use the stage against you.
• Exactly What It Says on the Tin
• Eyes of Gold: And they glow, too.
• Mama Bear: If the theory is to be believed, and it's helped along by the fact that she has a reversed version of Jin's tattoo and starts off with Jun's moveset.
  • Not to mention Ogre's ending, where Unknown has a Big Damn... Something moment to save Jin from being absorbed by Ogre.
    • Confirmed in the sequel. She is Jun.
• One-Winged Angel
• Power Tattoo
• The Reveal: Jun serves as the Final Boss in Tag 2. When you beat her in the first round, she becomes Unknown.
• What Could Have Been: According to the Tekken 6 artbook, she was meant to be Jun's younger sister. This was dropped when TTT became a spin-off.
  • Giant Space Flea from Nowhere: What she ends up being due to the above. Less so in the second one.
• SNK Boss: Not so much in the first Tag title, but moreso on the 2nd title. Let's see here. Rather large health bar with the ability to recover health? Check. Counters just like Jun Kazama but much stronger and with higher priority? Check. Using the purple goop stage against you? Check. A move that can reduce your health to 1 point while force-tagging your partner in? Check. Attacks from above and/or below that can't be anticipated and is very punishing? Check.