Yasunaga, Kenji was an alias used by voice actor Mizushima, Yu (birth name Noda, Kenji) when he recorded the opening theme and first ending theme to Ai No Senshi Reinbooman (Warrior of Love Rainbowman) in 1972.
He's done many anime voice roles. His tokusatsu roles are:
2007 Juken Sentai Gekiranger - Elehung Kambou (voice)
2013 Zyuden Sentai Kyoryuger - Sorrowful Knight Aigaron (voice), President (actor)
2014 Zyuden Sentai Kyoryuger vs. Go-Busters: The Great Dinosaur Battle! Farewell Our Eternal Friends - Sorrowful Knight Aigaron (voice)
2014 Kaettekita Zyuden Sentai Kyoryuger 100 Years After - Jealousy Knight Hoshigaron (voice)