If seven is a good number for samurai, as Akira Kurosawa proved with his classic 1954 movie, then how about 13?

The math works out just fine in “13 Assassins,” a remake of a ’60s Japanese film. The new version is directed by Takashi Miike, who tones down the derangement found in his previous films “Audition” and “Gozu” in favor of a more straightforward (but still plenty violent) tale of samurai action.

Set in the mid-19th-century, “13 Assassins” begins with a political directive: Someone’s got to stop Lord Naritsugu (Goro Inagaki), the depraved half-brother of the shogun. If Naritsugu ascends to power, a dark age will surely begin.

And so a rival lord bids the determined samurai Shinzaemon (played by the charismatic Koji Yakusho, from “Tokyo Sonata”) to assemble a team of warriors to get Naritsugu. The selecting of this samurai squad is a sure-fire movie formula that has worked in everything from “Seven Samurai” to “Ocean’s Eleven.”

Meanwhile, Miike is making sure we understand just how monstrous the villain is, with a series of scenes that detail Naritsugu’s sick habits. These scenes are not for the faint of heart.

The second half of the movie portrays the execution of the plan, as the 13 assassins lay a trap for their quarry. It culminates in a gigantic fight sequence in a town booby-trapped to help the small crew defeat Naritsugu’s 200-man army.

Showers of flying arrows and buckets of blood follow. “13 Assassins” lives up to its premise, as the single-minded quest to kill the bad guy is pursued with steely intensity. On that level alone, the film is an unqualified success.

We also get different viewpoints on the samurai code, which is portrayed as already out of fashion in this era.

Naritsugu’s chief protector (Masachika Ichimura) isn’t evil himself; he took the thankless job as a way of advancing his career, and even though he might hate his boss as much as the 13 assassins do, he’s got his sworn oath to fulfill.

If the film sounds like a throwback, it is, sort of. But along with the traditional samurai codes and such, Miike brings his ability to go way, way over the top at times: when a building full of soldiers explodes and a gusher of gore erupts like Old Faithful, you know the director is indulging himself a bit.

“13 Assassins”

A depraved feudal lord must be stopped, and a rival assembles a squad of 13 samurai to do the job. While director Takashi Miike occasionally indulges his penchant for over-the-top craziness, most of this movie plays as a straight-ahead action film, and an unqualified success on its own terms. In Japanese, with English subtitles.

Rated: R for violence, nudity

Showing: Varsity