A young boy named Kotaro and his dog Tobimaru are on the run from assassins from the Ming Dynasty, who follow a prophecy that calls for the child's blood as the main ingredient to the secret to immortality. Along the way they meet a skilled, namelessronin, who keeps his blade tightly bound to its sheath and unable to be drawn. Kotaro offers to hire the nameless man for protection on the way to the nearest temple, but the Ming aren't so easily deterred.
This anime provides examples of:
Ambiguous Ending: See Bittersweet Ending and Kill 'em All. The gist of it is that Kotaro and Nanashi are riding away, victorious. Kotaro seems happy, but his final smile is nervous, Nanashi is hunched over and half asleep, and the final shot shows blood dropping from the horse's back.
On the one hand, this is enough evidence to suggest Nanashi could die from his wounds.
On the other hand, Nanashi took no explicitly fatal wounds, his worst ones being an impaled forearm and a gutshot that was deflected mostly by his jade stone—both serious, but rather underwhelming for a death in fiction. He also ran several miles before he got those wounds, which would mean he would be asleep on his feet from exhaustion anyway.
Annoying Arrows: Averted most of the time, but played straight with the Chinese soldiers. Justified as they were taking drugs that caused them to Feel No Pain.
The Archer: Jyuurouta is able to out-snipe and kill one of the supernaturally strong Ming warriors and is praised by Shogen, his superior and mentor, as being skilled with a bow.
Arrow Catch: Fuugo. Not so much a catch as letting it slam into his forearm.
Art Evolution: A minor case when comparing the pilot to the finished film.
Automaton Horses: Nameless discusses the importance of proper horse care early in the movie. Later on, a messenger rides his horse full-tilt to deliver an urgent message, whereupon the poor thing collapses. And finally, horses get targeted for attacks. A lot.
Badass: Everyone, especially Luo-Lang, Nanashi, and the Shogunate and his Number Two.
Judging from No-name's past and similar skills and lifestyle, it's likely that Luo-Lang's first language is Mandarin. His accent is very good (though only for a foreigner); it's his perfect delivery and his awesome bass voice that's about as far from "Asian" as a voice can reasonably be said to get that's off-putting.
Black Speech: Actually just Mandarin with a heavy Japanese accent, but it has the same effect. In the English Dub, the Mandarin is actually well done and natural sounding, so the effect is somewhat mitigated.
Breaking the Bonds: Involving the ropes binding Nanashi's sword together. Also known as a Peace Knot. The cause is to let people know you're not planning to kill anyone today, as it renders you unable to draw your sword in a hurry. Obviously, breaking it has rather...dramatic implications.
Chekhov's Gun: Luo-Lang manages to overpower Nanashi in their fight leading to what was almost a Mutual Kill, but the jade trinket saves Nanashi and allows him to fatally stab Luo-Lang. Nanashi's dye nuts also find an application in the final battle.
Chinese People: Only distinguished by red cloaks and a different language. And funny hats. And a slightly different skin tone. And mildly stereotypical fashion sense. And amazing fighting prowess. And drugs.
Clean Cut: Luo-Lang does this to Byakuran's arm when he aims his gun at Nanashi and Kotaro, because Luo-Lang wants to fight.
Arguably the one who is the least Combat Pragmatist would have to be Luo-Lang. But when you're a foot taller than everyone else, and hopping around like Yoda on crack, you don't really HAVE to fight dirty. The dirtiest he gets is using a corpse as a shield to rush a bunch of archers.
Despair Event Horizon: Kotaro after he's turned over to the Ming. He's been betrayed by the people he trusted, he thinks Nanashi is gone, and he's going to be killed. The expression on his face is pure despair.
Even Evil Has Loved Ones: Itadori, the backstabbing, power-hungry warlord, is shown to genuinely care for his family during their brief scenes together.
Every Japanese Sword Is a Katana: Averted; only one main character uses an actual katana. He's also the only main character from Japan that uses a sword. Most of the main combatants are from China. Luo Lang's sword is a dao, as are Fuugo's twin swords. Extra points to the Chinese man using a tri-section staff with scythe blades on it though.
Exotic Weapon Supremacy: Averted, but not inverted. Exotic weapons are shown to be just as effective as more mundane weapons, being more effective in some situations, less effective in others. The difference is the strength of the character. On the one hand, a musket is more or less a Game Breaker; on the other hand, a Japanese spear-man has every advantage except speed, which he doesn't need.
Example: Fuu gets up and wanders around looking for his sword with a broken arm. And said sword blade STICKING CLEAN THROUGH HIS NECK. One of the rare examples where coughing blood is actually justified. He gets about 5 steps before he collapses.
The Ghost: The Chinese Emperor's desire for immortality is what sets the entire plot of the film in motion; but he never makes an on-screen appearance, he's only mentioned in passing by the Chinese warriors. There's also the eunuch who started the whole thing by making the prediction.
Hero of Another Story: Itadori and Jyuurouta seem to have their own plot in the background, which we only see a few scenes of.
If you watch closely, it appears that Itadori and Nanashi were a part of the plot that raised up the lord that Itadori eventually betrays with Jyuurouta's help. Itadori does say that he's only met one person who was at a level of skill on par with Luo Lang...
Homoerotic Subtext: Fuugo seems to be attracted to Luo-Lang; this is lampshaded by another character at one point while the latter is on a mission.
"You almost look like a wife who has lost their husband."
Human Shield: Luo-Lang uses an unfortunate soldier's corpse to block arrows.
Instant Death Bullet: To be fair, it left a grapefruit-sized hole in the guy's chest. Lead bullets aren't too subtle.
Invulnerable Horses: Completely averted. Plenty of fighters are willing to kill and maim horses to bring down their riders, including stabbing their throats with throwing weapons and slicing off their legs mid-run during a battle.
Jerk With A Heartof Gold: Nanashi, at first, due to Kotaro being the same way out of suspicion. Soon enough, no one bothers continuing it and they're mostly affectionate towards each other.
Katanas Are Just Better: Averted; only one main character uses an actual katana, and the weapon itself isn't that much better. Also a case of Shown Their Work as a Katana isn't meant to be used to hit other blades, doing this destroys Nanashi's sword in the final fight as it snaps in half and is shown to be serious chipped.
Kill 'em All: The ending is rather vague, so you can interpret it as the only survivors being Kotaru and the dog. Nanashi survives the final battle but is heavily wounded, barely conscious by the end and blood can be seen in the snow behind him as he and Kotaru ride into the sunrise. The argument against it being that we only see one really bad wound (an impaled forearm) and a bunch of cuts, and the marathon he ran before he got those would mean he would be barely conscious in any case. Regardless, it all comes down to perception.
Licked by the Dog: Tobimaru is instantly fond of the shady vagrant who's shown up in his young master's shack.
Though it's apparent that Nanashi starts to develop feelings for Kotaro and a sense of responsibility.
Made of Iron: Nanashi survives a building collapsing on him (which gives him a restorative nap) and an impaled forearm without really flinching. He accumulates about a dozen cuts along with those, in addition to taking multiple multi-story drops onto scaffolding.
Major Injury Underreaction: Standard for the Chinese due to their drugs, but the elderly, frail Lord Byakuran probably sets the record. Cutting off his arm only makes him annoyed at you.
Master Swordsman: Most notably Luo-Lang and Nanashi, though there are a few more like Fuugo who are also definitely skilled.
Meaningful Echo: "I wasn't talking to you, I was talking to that dog of yours."
Luo-Lang, a blonde-haired, blue-eyed European; Bai-Luan calls him a "Western barbarian" at one point. One of the best fighters in the movie.
Possibly the other best fighter, Nanashi. He is likely mixed, given the fact he's got red hair in an anime without Anime Hair, though through the use of dye he does perfectly pass for Japanese. However, red hair is possible for a completely Japanese person, just incredibly rare.
You could even call this "Mighty Foreigner, the movie"; in terms of fighting skill, any and all Japanese from the bandits to the soldier mooks and up to a Shogen's personal followers are all outclassed by the Chinese, requiring them to Zerg Rush for any measure of success. And in turn the Chinese People are outclassed by Luo-Lang and Nanashi, which as said above both may have non-Chinese/Japanese ancestry in their blood.
This is also a Deconstructed Trope, as despite their prodigious skill, Luo-Lang and Nanashi are not welcomed in Japan, with the townsfolk thinking Luo-Lang is literally a monster and Nameless hides his red hair to fit in, as others didn't accept him.
The Nameless: The titular stranger has no name, adopting different titles depending on the warlord he served at the time. He is usually referred to as "Nameless" ("Nanashi" in the Japanese).
Shown Their Work: A Katana isn't meant to be used to hit other blades since they're actually fragile, doing this destroys Nanashi's sword in the final fight as it snaps in half and is shown to be serious chipped besides that.
Single-Stroke Battle: Somewhat justified, as in every case the single stroke nature comes from disproportion between fighter's skill and one side greatly outclassing the other.
Almost all Red Shirts take a hit and die in fountain of blood.
Snow Means Death: The ending fight scene takes place during what seems to be the first snowfall of the year.
The Starscream: Shogen Itadori has no interest in saving his liege but only advancing his position. He reveals this by having his top pupil shoot the Daimyo, who was a hostage at the time.
Storming the Castle: What initially starts out as a plot to save the Japanese liege-lord turns into an all-out war between the races.
Super Soldier: Only because the Chinese PeopleFeel No Pain. Right up until they run out of drugs and end up in withdrawal, though whether or not that was withdrawal or just the individual in question finally reacting to the massive amount of torture he's experienced, but couldn't feel earlier, is up debate.
Sword Fight: The final sequence of fights are excellent examples of more realistic Wuxia style examples in animation.
Theme Music Power-Up: Played straight, then subverted once Itadori is shot to death. Though at that point, it's up in the air who normally should have gotten the power-up.
Throwing Your Sword Always Works: Used early on by Luo-Lang, and later half subverted when Nanashi does this then realizes he's weaponless afterward, and has to fight off several opponents without it. Though the second one defies the laws of physics with its effectiveness; at least Luo-Lang put some arc on his. Later still, Luo-Lang throws his broken sword at Nanashi, knocking him off the platform they were fighting on. It's fair to say that the the film loves this trope.
Translation Convention: There are several scenes in which the Chinese characters find themselves alone and they seem to speak Japanese instead of Chinese (or, in the case of the dub, English).
Wouldn't Hurt a Child: Because of his backstory where Nanashi was forced to kill two to serve his lord (an act he considered abhorrent then), he would never do the same again (and in fact refused to draw his sword because of it).
Worthy Opponent: Luo-Lang views Nanashi as one, killing his superior for the chance to fight him.