Kamen Rider X Opening from Five Riders vs King Dark with subtitles! I have no idea who did the subtitles, but I know they did most of the Showa Kamen Rider movies. (I know they did ZX, the Super 1 movie, and Eight Riders vs Galaxy King; I have found 3 of the 4, I am still looking for Eight Riders vs Galaxy King)
All credits go to Toei, Ishimori Productions, and whoever subbed this.