To most film fans, he is best known for his various roles in The Street Fighter film series, the Yakuza Cop film series, as well in other films such as Samurai Reincarnation, Wolf Guy, Doberman Cop, Message from Space, and Golgo 13: Assignment Kowloon. His final film role will be in Bond of Justice: Kizuna, which will be released after his passing.
But to most tokusatsu fans, he is best known for playing one of the few early superheroes on TV, namely Kotaro Ran/Seven Color Mask in Seven Color Mask and Goro Narumi/Messenger of Allah in Messenger of Allah. He also made a cameo appearance in Space Sheriff Gavan in a very important role in the series. In addition, he also founded Japan Action Club (JAC) in order to develop the level of martial arts seen in Japanese TV and film. This company will be later known as Japan Action Enterprises (JAE) with its members being regular suit actors in Toei's Kamen Rider and Super Sentai Series.
From all of us here, thank you for the memories.
[Source: Variety, Wikipedia (for additional actor details)]