If you're considering watching Sword For Truth because of it's comparison to Ninja Scroll (which seems to be something of it's tagline) or for it's super manly cover I can save you 49 minutes by telling you to rethink that whim of yours. It's bad. The plot is frustratingly open-ended and unclarified. The art is super mundane to Big O proportions. There is some gratuitous amounts of sexy behavior like... sex abound, though. If that's what you watch anime for.
As the story goes, a mercenary just happens by Edo one night and slays a giant tiger gaining the attention of the men who had their princess snatched during what will be known as the old "distract the guards with a giant roof-walking tiger grab the princess and run" fiasco. He then commences to go trade a relic of her fathers as ransom for her at a temple, but not before randomly sexing up some pickpocket he embarrassed (by cutting off her clothes) earlier. As he whisks her away from the group of ninjas trying to kill them, another group of ninjas charges in to clash with those chasing them.
On their way back to Edo, he fights two superpowered villains which he kills with ease. Somewhere in there we cut to another assassin who fights with his fists and kills a man. When they get back to Edo, the clan deems that the assassin who saved the princess must be killed because he has...seen her (beware anyone with eyes). However, she intervenes and they let him go. The movie ends with the sword wielding assassin and the fist fighting assassin walking past each other and saying something I assume is meant to be meaningful but just comes out as pointless as the movies plot.
Now, if that plot seems nonsensical I promise you I am not leaving parts out. It really makes that little of sense.
The main character is so cookie cutter I feel as though I should roll some dough to use him on. He's dry, humorless, emotionless, and great in bed. Everything anyone dreams a samurai assassin should be. In the fights during the series, he ends any confrontation with only a few blows or maybe a hundred. I don't know they did the 80's anime thing where they show still images but move the camera. Not to mention there were a whole slew of characters that appeared to be significant to the plot that were never seen again. Even the man I thought to be the main villain bent a ninja over his head like a hat and was never heard from again, he didn't even die!
I am left so confused and frustrated by this I shall rate it on a weird scale I made up.
-10 for confusing plot
+5 for a sex scene that went of forever >_>
+2 for lots of nudity
+8 for lesbian sex scene with opium based debauchery
-10 for all these random characters that seemed like they had purpose but did not.
-5 for trying to be deep and failing.
-5 for the main character never being hurt ever
+2 for the random woman of the night with a woman eating a baby tattooed on her back.
-30 to +17
I'd say with comes out to being a terrible watch. Unless you like sex and being confused. The sex is early in the film to so you don't have to waste a bunch of time.