Here's a couple more:
Yoshinobu Kaneko starred as Blue Shadow, the kid sidekick of the titular ninja superhero Masked Ninja Red Shadow (Toei; 1967), and also played the boy ninja hero, Watari, Ninja Boy (based upon Sanpei Shirato's manga). There were many other Watari films, including compilation films which used episodes of Red Shadow, passing Blue Shadow off as Watari!
His brother, Mitsunobu Kaneko, starred in the title role of the TV series, Akuma-kun (Toei; 1966), and was the star of Mitsuteru Yokoyama's Giant Robo (Toei; 1967), AKA: Johnny Sokko and His Flying Robot! Sadly, he passed away in 1997. As far as I know, details of his death have not been disclosed, even to this day.