I am not sure what I want to write about Shikabane Hime. My brother told me about the show after he watched it on Hulu.
The art and camera perspectives remind me of FLCL, though even with the undead monsters it lacks the latter's weird factor. It is also not as colorful; the dark subject matter and constant reference to death demands a much more subdued color palette.
When people die with strong regrets or obsessions that tie them to the world, they can come back to life as shikabane. Shikabane are dead, immortal, regenerating monsters who exist to fulfill their regrets and obsessions. They have no compunction against killing humans and, in fact, many actively seek to kill. Some shikabane have even greater supernatural powers called curses. The effects of these curses are varied but they can be profound. One shikabane reflects any injury to itself back on its attacker while another can open a "trench", or extradimensional space, to isolate or trap its enemies or prey.
In order to protect humanity from the ravages of shikabane, the Kougon Sect buddhist monks utilize shikabane hime, or shikabane princesses, to fight against them. Shikabane hime are shikabane; each of them died and came back as a shikabane with the same supernatural strengths and regenerative capacity. They may even have come back with regrets and obsessions like shikabane; it is not 100% clear from the series (so far; I am at episode 15/25) whether they return on their own but I suspect it is true; it is also unclear if they have to be female (so far all of them are female and the -hime honorific means princess) (edit: in a later episode, it is mentioned that the Kougon sect no longer possesses the full knowledge of the ritual to create shikabane hime and so they can only contract with young girls of a certain age range). In the window of time between the shikabane's return and her descent into inhumanity, the Kougon sect is able to bind her to a contracted monk (most monks are men but there is a female monk).
Once bound to a contracted monk, the shikabane becomes a shikabane hime. Her descent into inhumanity ceases (or maybe slows to a glacial crawl) and she derives her existence from the monk's life force (called rune) rather than her regrets and obsessions. The spiritual and vital strength of the monk also powers the shikabane hime's supernatural strength; some shikabane hime are stronger than others and it is mentioned that it has to do with the strength and purity/holiness of the contracted monk (one of the stronger shikabane hime belongs to the heir of one of the Ten Holy Families and this is mentioned by one of the main bad guys as a good reason to flee a battle). The ultimate goal of the shikabane hime is to kill 108 shikabane. Once they have accomplished that, they can move on to tengoku (heaven), having paid for the crime of becoming shikabane.
The main plot revolves around two conflicts. The background conflict is a split of the Kougon sect into two factions. One supports the use of shikabane hime in destroying shikabane while the other considers shikabane hime to be no different than shikabane and their use should be stopped as it is a defilement of their order. The head of the Kougon sect belongs to the former faction while the head underling (and several other high ranking monks) belongs to the latter. The main conflict involves a group of powerful, cursed shikabane called The Seven Stars. They believe they have progressed beyond regrets and obsessions. They believe that immortality and the powers of shikabane are inherent to their nature and that they represent the only true human beings, having shed the weaknesses of death and regrets. Another villain, the Traitor Monk, used to be a contracted monk. He apparently switched factions in the Kougon sect and killed his own shikabane hime. He originally sought to create more shikabane to steal some of their power and he seeks to destroy either the whole Kougon sect or just the faction that uses shikabane hime. He joined with the Seven Stars after being defeated by the monks but the Stars are not particularly beholden to him.
The parallels between the contracted monks/shikabane hime and the paladins with their battle angels are obvious; it was particularly underscored in an episode where the strongest shikabane hime performs a sword slash that throws out a huge blast of spiritual power; the effect was almost identical to what I imagine el armor del oro's purging flame looks like.
Throughout the series, I have viewed the monks as a pagan analog to the paladins and thought about how they could work together against a common enemy. I want to wait until the end to determine where it would be best to introduce them but I have no qualms with discussing the moral and theological implications of the shikabane hime. They are very similar to Veronica in that they have cheated death and overcome the tainted nature of undeath to work for good. They differ in that apparently they came back willingly (through their regrets and obsessions).