It is set during the Heian Period (9th-12th centuries). Yone and Shige, mother and daughter-in-law, are peasants living in a hut. They are all alone because their son/husband was forcibly dragooned into the army, and they haven't heard from him since. A small band of samurai, seemingly having escaped a battle, swarm down on the hut and rape and murder both women, setting the hut on fire as they go. But their bodies are strangely intact, even after the cabin burns to ash and a few charred timbers. A black cat emerges from the wilderness and licks the faces of the dead women.
A samurai approaching the Rashomon gate of Kyoto sees an eerie looking mature woman in a kimono. The strange-looking but attractive woman lures the samurai to an elegant mansion in the forest, and introduces him to a younger, very good-looking, but similarly eerie woman. The younger, hot woman lures the samurai into the bedroom. They embrace passionately—until the younger woman kills him by ripping his throat open with her teeth. The victims are always found on the remains of the burned-out hut. This happens multiple times.
Meanwhile, a young soldier named Hachi escapes a bloody battle, bearing the severed head of an enemy general. He makes it back home after a three-year absence. The shogun, impressed when the soldier delivers the head of his enemy, makes Hachi a samurai. He then gives Hachi a task: find and destroy the ghost/monster that is killing samurai. Hachi accepts the challenge, travels to the Rashomon gate, and sees the mature woman...who looks familiar.
- Agent Scully: Raiko refuses to believe the tales of a murderous ghost, insisting to Hachi that it must be a monster of some sort.
- Answer Cut: Raiko, furious that his samurai are too scared to go after the ghost, says "Isn't there anyone willing to kill this monster?" Cut to
- As You Know: Raiko is addressed with "Raiko Minamoto, you are the leader of the samurai."
- Boy Meets Ghoul: Hachi has a passionate affair with the ghost of his wife, although he isn't sure if it's really his wife, or a ghost that has taken her form.
- Cats Are Magic: The black cat apparently brings the women back to life, or rather, undeath. It also sort of merges with the identity of Yone, who sometimes becomes a feline humanoid.
- Creepy Crows: A crow sets down on the dead, staring body of the first samurai victim.
- Decapitation Presentation: Hachi earns promotion to samurai by chopping off the head of an enemy general and presenting it to Raiko.
- Downer Beginning: Two innocent peasant women are raped and murdered.
- Downer Ending: Shige sacrifices herself and winds up going back to the underworld. Yone, who has fused with the cat creature and seems to be more demonic, tricks Hachi into giving her arm back. They fight, and Yone does not try to kill him, but he seems to go mad. He collapses and apparently dies in the ruins of their hut.
- Ghostly Chill: The first samurai feels a chill when the black cat enters the room.
- Ghostly Glide: There's a mud puddle on the way to the ghostly mansion. Every time Yone has to cross it, she sort of flies over it rather than stepping.
- Heroic Sacrifice: Shige has seven days in which to kill her husband, now a samurai, per the Deal with the Devil. She can't do it, and winds up literally going to hell rather than kill her husband.
- Historical Domain Character: It just so happens that Raiko, the governor of the region who sends Hachi off to kill the ghost, was a real guy.
- The Mirror Shows Your True Self: As Hachi follows the ghost of his mother he sees the reflection of her face in a pool. She looks like a ghastly demon instead of the human face she presents to Hachi. After seeing this he attacks her with his sword.
- Ominous Fog: The mansion and grounds, where the ghosts of Yone and Shige seduce and murder samurai, are usually covered in spooky fog.
- Repeat Cut: Repeat Cuts are used several times when Yone is leaping around fighting a samurai, to make her movements seem even more creepy and unreal.
- Snow Means Death: Ends with Hachi, who has apparently died, lying on the floor of the ruined hut as snow falls and covers his body.
- Vengeful Ghost: Yone and Shige swore a vow to the god of the underworld. In return for assuming corporeal form again, they must kill samurai, and drink their blood, in revenge for their murders.
- War Is Glorious: Raiko loves war, rhapsodizing about how it's a great way to get fame and fortune and power and women. He can't quite comprehend how peasants could hate the samurai, eventually telling Hachi that peasants aren't people anyway.