Tetsujin first appeared as an unlockable character in Tekken Tag Tournament, and did not return to any other Tekken game. Tetsujin is a metallic version of Mokujin, and like Mokujin, has no fighting style of his own. Instead, he chooses another playable character's fighting style and uses it. Tetsujin's fighting style changes after each round, and also when tagged out and back in.
Tetsujin makes a cameo as the training dummy in Tekken 5.