I want to find out the name of a contemporary Japanese cop film.  The main character is this detective that wears a bucket cap, walks funny, his always beating up people, and he does not like to use guns instead he has a water gun.  This detective is looking for a hit man that kills his victims with a sword.  The majority of the violence is physical; his entire department interrogates suspects with sticks, kicks and fists.  I hope this is enough for someone to recognize it.
Thanks
