Doberman Cop (1977)

A strange mess of a movie. Its plot line contains Sonny Chiba as hick cop from Okinawa coming to Big City Tokyo, an obsessed yakuza turned music manager, the Japanese ancestor of "Pop Stars", a pig, a serial killer, Dirty Harry's favorite weapon, a biker gang, unfunny humor, vigilante "justice" and a singer with a past. If I have forgotten anything, you can be sure it is in there somewhere.
The confusing mess of a plot is directed by Kinji Fukasaku in his patented dynamic and/or disorienting jitsuroku style and to my surprise actually makes for a very watchable film.
It seems as if the initial plan was to cash-in on American and Italian Tough Cop movies, but somewhere on the way someone (Fukasaku?) decided to inject an unhealthy dose of Japanese obsessions and plain weirdness. I wouldn't go as far as calling it a deconstruction of the genre, although it's nearly there.