After working for an electric power company for a year after graduating high school, Shiro Koshinaka enrolled in the All Japan Pro Wrestling Dojo in August 1978, training under Giant Baba and Kazuharu Sonoda.

In 1984, Koshinaka went on an excursion to Mexico, wrestling as Samurai Shiro in Empresa Mexicana de la Lucha Libre, where in July, he lost a Hair vs.

In August 1990, he went to Austria to Otto Wanz's Catch Wrestling Association to challenge Steve Wright for the CWA World Middleweight Championship, but failed, as he lost on the tenth round.

Returning to Japan in September 1990, he was the very first opponent for Mutoh's alter-ego, The Great Muta, and also joined Tatsumi Fujinami's Dragon Bombers.

They were also wrestle in WAR, which they feuded with several stars including Genichiro Tenryu, Ashura Hara, Takashi Ishikawa, Hiromichi Fuyuki, and Koki Kitahara, among others.

After Heisei Ishingun disbanded, Koshinaka rebounded and regained the IWGP Tag Team titles in March 1999, this time with Kensuke Sasaki.

He took part in a tournament for the Triple Crown Heavyweight Championship that was vacated by Kenta Kobashi; he defeated Johnny Smith in the first round, but lost to Toshiaki Kawada in the semi-finals.

On January 4, 2016, Koshinaka made a surprise return to NJPW by taking part in the New Japan Rumble on the Wrestle Kingdom 10 pre-show.