Vigilante in the Funky Hat

Hepcat in the Funky Hat is a 1961 action comedy film directed by Kinji Fukasaku and starring Sonny Chiba. It was followed by a sequel, Hepcat in the Funky Hat: The 20,000,000 Yen Arm, which was released one month later that same year and was also directed by Kinji Fukasaku with Sonny Chiba and Shiro Okamoto in the same roles.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.