CONTAINS SPOILERS THWACK EEEEK OOF AAARGH
Well, it's not the profoundly stupid but undeniably enjoyable Ninja Assassin, but as a DTV action quickie it's actually rather good and a lot more fun than its credits would lead you to suspect. It hails from the frankly variable Nu Image stable and is actually closer to their cheapie video fodder output than their occasional stabs at Proper Cinema like Righteous Kill and Rambo (not that either of them were actually any good and Rambo in particular was unspeakably terrible).
Ninja tells, somewhat unsurprisingly, of a Good Ninja (our hero Scott Adkins: stolid, invulnerable, with absolutely no charisma whatsoever) taking on a Bad Ninja (evil Tsuyoshi Ihara: scarred, embittered, insane) who wants something called the Yoroi Bitsu. This is a box of ancient miscellaneous ninja bric-a-brac: arrows, throwing stars, poison, blowpipes and a suit of ninja armour, probably accumulated at a ninja car boot sale. The Bad Ninja, having been thrown out of his dojo for demented acts of violence, now works as an assassin for a sinister cabal of industrialists who gather in a basement wearing robes and branding each other with the secret sign. Several niftily choreographed fight scenes and dozens of corpses later, it all ends in the inevitable crunching showdown between the Good and Bad ninjas, while the Good Ninja's girlfriend (a ninja in her own right) looks on.
It's beyond silly and ludicrously violent, full of all the things the BBFC never used to allow such as throwing stars and rice flails. It's not well written (the plot is absurdly simplistic) and not well acted but the crash bang wallop of the combat sequences and the plentiful bloodshed keep it rattling along effectively enough. Worth a look, but any kind of brain is not required.