Seiji Sakaguchi is a Japanese retired professional wrestler and judoka, Sakaguchi holds a 7th dan red and white belt in Judo. Sakaguchi was a mainstay of New Japan Pro-Wrestling (NJPW) and also competed for the World Wide Wrestling Federation and the National Wrestling Alliance. His sons are professional wrestler and mixed martial arts fighter Yukio Sakaguchi and television actor Kenji Sakaguchi. Sakaguchi currently works for New Japan as an advisor.

New Japan Pro-Wrestling (NJPW) is a Japanese professional wrestling promotion founded on January 13, 1972, by Antonio Inoki, and based in Nakano, Tokyo. It is currently owned by card game company Bushiroad, while TV Asahi and Amuse, Inc. own minority shares of the company. Naoki Sugabayashi has served as the promotion's Chairman since September 2013, while Hiroshi Tanahashi has served as the president of the promotion since December 2023.