Kintaro is a white pug with a distinctive black-and-white patch on his mouth and ears. His hair is black and reaches his shoulders and one band is tied with a red rubber band in a ponytail at the top. His eyes are brown. Dressed in red clothes with a gold Japanese sign in the middle. He has sandals on his feet and golden bracelets on his hands. On his back he has a goldfinch.
Kintaro was born in the shadow of a prophecy that said he would be the bearer of divine powers with which he was to help the inhabitants of his world. For this reason, Kintaro had been treated with awe-inspiring reverence since his birth, which, however, turned him into a pampered, distracted brat.
Kintaro spent his first years as novices of a certain religious order. When he was old enough, he was picked up by a samurai under the leadership of the warrior Akemi to be escorted to the Order's temple palace. However, the mass murderer Jei, who had been possessed by a demonic spirit, learned of Kintaro's existence, and in his delusion to act according to the will of the gods, decided to eliminate Kintaro. For this purpose, Jei brought a squad of samurai into his spiritual power and subordinated them to the order of the mercenary Sumo Kuma.
Sumo Kuma's squad brought Akemi, Kintaro and their samurai to a village, and set up a bloodbath, which only Kintaro and Akemi could escape alive. However, previously, Akemi had sent a message to her friend, the ronin Miyamoto Usagi, to meet her in that village. Usagi arrived too late to assist them against Sumo Kumas's gang, and since Akemi was too badly injured to continue the journey, Usagi took over the task of taking Kintaro to safety. When Jei learned that his arch enemy, Usagi, had intervened, he brought the Teenage Mutant Ninja Turtles into his world to liquidate Usagi under the influence of his mind control. The Turtles confronted Usagi, but during the battle the effect of Jei's control over their minds was neutralized, and after the turtles learned of Usagi's task, they joined him and Kintaro after Usagi had assured them the monks of Kintaro's order may know a way to get them home.
- Kintaro is a possible counterpart of Prince Noriyuki from the Usagi Yojimbo comics.
- Kintaro is named after and based on a legendary Japanese folk hero Kintarō (金太郎, "Golden Boy"). Kintarō, allegedly based on a real person named Sakata Kintoki, was a young boy in a red haragake (apron) who had super strength and fought with an axe. The Kintaro in TMNT/Usagi's world is also referred to as the "Golden Boy", wears a red haragake, and also specializes in utilizing an axe.
- The kanji on his haragake, 金 (kin), is the first character in his name and means gold.