During his childhood, he trained in the fighting style of the Aizu clan, called oshikiuchi.In 1882, Saigo moved to Tokyo and in August of that year, he enrolled at the Kōdōkan, becoming Jigoro Kano's second student.

Non-judo people in particular were most impressed at the spectacle of such a small man so easily throwing a much bigger opponent, so much so that Saigo's exploits induced many others to take up training in judo.

[5]Similarly, Saigō fought on behalf of Kodokan in 1884, when three fighters of the Yōshin-ryū jūjutsu school named Matsugoro Okuda, Daihachi Ichikawa and Morikichi Otake came to challenge their members.

[6] Saigō also took part in the Kodokan-Totsuka rivalry, participating in the tournament between Kōdōkan and the Totsuka branch of Yōshin-ryū hosted by chief inspector Michitsune Mishima.

[7] Controlling the match, Kochi tried to throw him with harai goshi and uchi mata, but Saigō slipped out and landed on his feet every time, making Entaro increasingly tired.

Although his head hit the ground, Entaro got up again, after which Saigo scored another yama arashi, breaking Kochi's shoulder and forcing him to give up the match.

[7] The Kōdōkan won most of the matches that day, and the rival school's master Hidemi Totsuka was forced to praise Saigō, saying to Kano "you really have a wonderful student.

"[8] Saigō also fought against Shusaburo Sano, a Totsuka jujutsuka who was supposedly strong enough to bend iron rods with his arms and shatter thick boards with his fists.