Masaru Yamamoto (山本 勝, Yamamoto Masaru; October 30, 1941 – August 28, 2010), known by his ring name Kotetsu Yamamoto (山本小鉄, Yamamoto Kotetsu) was a Japanese professional wrestler, referee, and color commentator for New Japan Pro-Wrestling. He was named "Kotetsu" ("Little Iron") by former Japanese pro wrestler Toyonobori after the famous knight, Aizu-No-Kotetsu. Originally a wrestler, Yamamoto was mostly known for his tag team the Yamaha Brothers with Kantaro Hoshino but made his biggest mark as a trainer in the New Japan Dojo having helped train Keiji Mutoh, Jushin Thunder Liger, Minoru Suzuki, Shinsuke Nakamura, and Masahiro Chono among others.
Source: “Kotetsu Yamamoto”, English Wikipedia (CC BY-SA 4.0), excerpt