If the makers of “Ninja Assassin” had created their entire movie in the spirit of the first scene (and a couple of others), all would have been just fine, at least for people with strong stomachs. That introduction, an over-the-top bloodbath intended to kick off a hyper-violent action spectacle, serves as a treatise on how saturated with exaggerated but realistic gore movies can be now with the advent of computer-generated imagery. The rest of the movie, however, descends into a long, agonizing torture of over-explanatory plots and unnecessary characters, brought together for cheesy, interminable battle sequences that don't have any of the fun of the first.
The story is obviously preposterous (it's ninjas) but the real problem is that it's too dumb and inconsequential to be entertaining. There are ninja-assassin clans going back centuries, we are told. Our hero, Raizo (Jeong “Rain” Ji-Hoon, a South Korean pop star), is a member of one, raised at a mist-covered mountain retreat where he is taught martial arts along with a philosophy of pain and violence. As an adult he's trailed by two agents (Naomie Harris and Ben Miles) from an international crime-fighting apparatus called Europol, which is somehow under the jurisdiction of Homeland Security and the CIA. All are after the ninjas for various reasons, none of which are worth recounting.
As for the men in black pajamas themselves, if you are one of the few people hoping for a semblance of the ninja of Japanese folklore, prepare to be deeply disappointed. These are a more pan-Asian type of assassin (preferring to speak English of course) and while they wield katanas and throw shurikens, their deadly skills also include turning into puffs of black CGI smoke and zipping around a la the ghosts in “The Grudge.”
A better filmmaking team might have turned the material into a memorable mix of action and humor, but, as envisioned here, “Ninja Assassin” would have to sneak up on someone to get a reaction. (R) 99 min. HIIII