Onmyoji

A 2001 Japanese fantasy film about Abe no Seimei. The sequel, imaginatively named Onmyoji 2, came out in 2003.

Set during the Heian Period (or a fantasy version thereof), Onmyoji begins with the story of how Prince Sawara was banished for a crime he didn't commit, and how he swore eternal vengeance. Cut to a long, long time after, when Douson is leader of the Emperor's onmyoji, and Abe no Seimei is an ostracised (but powerful) loner. A mysterious lady pleads with Seimei for a love spell that will bring the Emperor back to her, but he refuses. Meanwhile, young court noble Minamoto no Hiromasa is in love - and also beginning a close friendship with Seimei.

What none of them know is that Douson is planning to bring down the Emperor. And then the newborn prince is cursed, Seimei is arrested and a demon stalks the Imperial Palace...

Onmyoji 2 is set some time after the events of the first movie and touches a bit more on Japanese Mythology, namely the gods and goddesses and the Izumo and Yamato clans. A demon is running loose in the captial, killing members of the nobility at random. What sets these murders apart from others is that one body part (an eye, the nose, a leg, etc...) on each victim is devoured for some unknown purpose. Fujiwara no Yasumaro, the current Right Minister to the Emperor, is worried about his daughter, Himiko, being possessed by the demon as she's been sleepwalking at night at the same time the killings began. The Emperor tasks Seimei with finding and exorcising the demon. Meanwhile, Hiromasa finds a new friend in Susa, a peasant boy, after following the sound of the latter's biwa melody. In the middle of all of this is the story about an Izumo village that was destroyed 18 years ago and the mysterious sword, Ame no Murakumo.

Behind the scenes, a mysterious man named Genkaku is employed by other members of the Emperor's court due to his "god-like" powers in a political gambit to bring disfavor to Seimei. However, Genkaku seems to be interested in other things...

Tropes used in Onmyoji include:

Above Good and Evil: A rare example of a True Neutral character using this argument.
Amemiko I Am Your Mother: The spirit of Tsukuyomi reveals what Genkaku's plan is to Seimei and Himiko, along with the truth of Himiko/Amemiko and Susa's parentage.
Asian Rune Chant: Seimei and Douson in the first film. Genkaku and Seimei in the sequel.
The Atoner: Fujiwara no Yasumaro raises Himiko as his own daughter out of the guilt as he's the one who led the attack against the Izumo village 18 years ago.
Artefact of Doom: The sword, Ame no Murakumo. The previous Emperor destroyed the Izumo village in order to obtain it and other riches. 18 years later, Genkaku uses its magic to finish turning Susa into Susano-o no Mikoto and destroy the capital.
Back From the Dead: Hiromasa.
Balancing Death's Books: Lady Aone offers her life in exchange for Hiromasa's in Seimei's resurrection ritual, although her immortality probably has a lot to do with it as well.
Break the Cutie: Hiromasa has horrible luck when it comes to his romantic relationships as both Sukehime and Himiko are both dead by the end of the films they appear in.
Chronic Hero Syndrome: Hiromasa.
Complete Monster: Genkaku has absolutely no problems with using his children as a way of getting revenge on the Emperor, even if it means sacrificing them.
Crapsack World: The only two characters in the film who are actually good people are Hiromasa and Lady Aone. Himiko and Susa when he's not being possessed from the sequel are also fairly good people.
Demonic Possession: Genkaku is using his son, Susa, as a vessel for the destructive god, Susano-o no Mikoto. Inverted somewhat with the seven murder victims who are also thought to be reincarnations of seven other gods with Himiko, the eighth and final victim, being the reincarnation of Amaterasu.
Died in Your Arms Tonight: Hiromasa, although he was shot several minutes beforehand, holds on long enough for Seimei to get there and fulfil this trope.
Dragon-in-Chief: Prince Sawara is only theoretically the main villain.
Duel to the Death: Seimei and Douson, eventually.
- Genkaku and Seimei have a duel at the climax of the sequel.
Dying as Yourself: Sukehime reverts to her normal self after choosing to kill herself rather than Hiromasa, and dies in his arms.
The End of the World as We Know It: Genkaku's plan is to destroy the capital and the land of the Yamato clan. He succeeds in effectively destroying the capital, but is ultimately stopped by Seimei and Hiromasa.
Evil Is Hammy: Douson and Genkaku like to occasionally snack on the scenery.
Evil Is Not a Toy: Genkaku calls upon the powers of the gods, namely Susano-o no Mikoto, to help him with his revenge. Susano-o no Mikoto obliges, but marks Amemiko/Himiko as the final sacrifice to awaken the deity's power. Nice job there, pops.
Evil Laugh: Genkaku oh-so-much.
The Four Gods: Seimei invokes these at one point.
Gorgeous Period Dress: Seimei is usually beautifully and colourfully dressed, as is Mitsumushi; most of the other characters, however, dress quite plainly.
Heroic Spirit: Hiromasa. He tries so hard.
Hey, It's That Guy!: Ujio/Kenji plays Douson.
Ho Yay: Seimei and Hiromasa. Seimei and Hiromasa. "Oh, I don't care about the world, but I'll save it if you really want me to."
- Comes up in the sequel too. They really don't want each other to die.
Ironic Echo: "When it is time to perish, we will all perish."
Japanese Mythology: Features prominently throughout, but notably in the second film.
Kill the Cutie: Hiromasa in the first movie. Himiko and Susa are both dead by the end of the second movie.
Loves the Sound of Screaming: Douson.
Manly Tears: Seimei, when Hiromasa dies.
Meaningful Name: Susa. He's being used as a vessel for the spirit of Susa-no-o no Mikoto, god of seas and storms. Depending on the kanji used, Himiko's real name (Amemiko) could refer to rain.
Mooks: The Imperial soldiers Douson has possessed by demons.
Moral Event Horizon: Genkaku didn't seem all that disturbed when he offers his children up as sacrifices to the gods or when he kills his wife.
Morality Pet: Seimei really doesn't care about the human world that much; Hiromasa is the one exception.
Music Soothes the Savage Beast: Hiromasa's flute playing help stop the possessed Susa in his tracks on more than one occasion.
Mythology Gag: Seimei often looks faintly vulpine; this is a reference to his mythological background where he was the son of a kitsune. Specifically referenced by Hiromasa in-universe; upon first being introduced to each other, Seimei playfully teases Hiromasa about the myth.
- Seimei's possible ancestry is brought up again in the second movie. Upon meeting Seimei for the first time, Himiko tells him that he looks like "a white fox."
Noblewoman's Laugh: Seimei.
Not So Different: Interesting example, in that Seimei acknowledges the similarities calmly enough. He's just angry that Douson killed Hiromasa.
Not So Stoic: While Seimei doesn't precisely count as The Stoic, one of the very few times we see him lose his composure is when Hiromasa dies and he ends up nearly hysterical with grief.
Onmyodo
Parental Abandonment: Himiko's real parents are either dead (Tsukuyomi) or have been driven insane and plan on using her as a tool for his revenge plot to awaken a god of destruction (Genkaku).
The Power of Love: How Sawara is defeated.
Roaring Rampage of Revenge: The events of the second movie are set off 18 years prior after the previous Emperor ransacks a village of Izumo tribespeople, killing all but Genkaku and his family, in the hunt for precious religious artifacts.
Sealed Evil in a Can: Prince Sawara. In practice, he's really more Sealed Pissed Off In A Can, he calms down fairly quickly once he's told his brother apologised.
- Susano-o no Mikoto's power seems to be sealed away in Ame no Murakumo and requires eight sacrifices in order for the god's power to be released.
Self-Disposing Villain: Douson, obligingly enough, kills himself after his defeat.
- Genkaku also dies after his defeat, though if he died of outside causes or something self-inflicted is ambiguous.
Seppuku: Sukehime, Sukehime's father, Douson.
Slashed Throat: A favourite method of death for the characters.
Spirit World: Or wherever the hell Seimei goes after Hiromasa dies.
- It comes up again in the second movie when Seimei and Hiromasa attempt to resurrect the spirit of Amaterasu.
Tomboy Princess: Himiko, to the chagrin of her father and handmaiden.
Tragic Villain: Genkaku goes mad when the Emperor's army destroys his village. Before that, he's shown to be a gentle husband and a good father.
Who Wants to Live Forever?: Aone. She doesn't.
Wholesome Crossdresser: After Himiko is killed by the possessed Susa and Genkaku ravages the capital, Seimei dresses up as the shrine maiden Ame no Uzume in order to open the gate to the realm of the gods so that they can resurrect Amaterasu.
Wide-Eyed Idealist: Hiromasa, especially when compared with Seimei.
Woman Scorned: Sukehime.