Production company did not acquire remake rights, resulting in a lawsuit and delaying the film's US release until 1967 (three years after its Italian release).
Yes, it is one of those three 1996 Bruce Willis movies.
Japanese, and, in fact, Kurosawa. He had a huge influence on the Western genre, not just through remakes. The film in question inspired not just the "unofficial remake", but two more films that comprise what is probably the most famous trilogy in the genre, and gave a certain young "Rowdy" actor is first big break (and one of his most iconic characters, though no one would be able to tell you his name).
The third movie of said Western trilogy featured a theme song that would become famous, and used by Metallica at the start of all of their concerts.
Lots of hints in there, though some are more subtle than others. I don't like to make things easy.