Jiro Sakata (坂田 次郎 Sakata Jirō) is the youngest brother of Ken Sakata and Aki Sakata. He also looks up to Hideki Go as his hero and is very enthusiastic about anything related to Ultraman and kaiju. He would occasionally assist MAT with regards to situations involving the monsters.
Jiro's final appearance was in Ultraman Ace episode 10. Like TAC, he was tricked into believing that Go had returned to Earth, when in reality it was Alien Antira that transformed into him. When he handed a box of red bean cakes to "Go" in the hospital, he was surprised when "Go" stabbed the cakes with the chopsticks in his left hand, when Jiro says Go should be a right-hander. The alien corrected its mistake, but Hokuto Seiji was already suspicious.
Later, when Hokuto told Jiro of the truth, he refused to accept it at first before pursuing Antira to the rooftop. He tried to fight the Alien only for him to take him hostage, but TAC freed him.
After Antira was beaten, Jiro looks up at the night sky, and the real Go makes a final communication to him, appearing briefly as an image, as Jiro recites the five Ultra pledges.