Satō is a young man who was a kenjutsu student at the Kamiya dojo under the tutelage of Kamiya Kaoru until the murder spree perpetrated by the false Hitokiri Battōsai Hiruma Gohei drove him and all his peers to leave. Even after the incident had been rectified, Satō still did not return to the dojo and, roughly two weeks later, went drinking with a fellow former student Hira and began drunkenly harassing townspeople. Picking a fight with a member of the Hishimanji Guren Gang, Hira and Satō drew their practice swords and broke their opponent's arm. With Hira's shoulder also injured, the duo were ill-matched when the remaining gang members appeared for revenge and fled to the protection of the Kamiya dojo, claiming to have been the victims. However, Hira and Satō's true actions were discovered and, after the Hishimanji Guren gang was driven off, they were told to never again hold a sword in their hands and forget that they were ever students of the Kamiya dojo.
Sato was a rather cowardly and shameful individual. Even after the fake Battosai matter was cleared, he didn't have the nerve to return to the dojo. He and Hira turned out to be more pathetic and despicable than they appeared to be, as after they got drunk ad started harassing the people, and injured a gang member, they stooped so low to run back to their former master, whom they had forsaken, and lied to her to save their own lives. This disgraceful act of cowardice ultimately costed them Kaoru's respect for them.
Satō and Hira appeared in Act 4 of the manga, but their adventure with the Hishimanji Guren gang was left out of the anime.