Necromancy

The art of reviving the bodies of the deceased. It revolves around manipulating the dead, death, and souls. The main restriction of the art revolves around how much time has passed since the soul has left the body. The best necromancer in Mibu Clan is Fubuki, followed by Saishi.

Pseudo Zombies
The main offensive weapon of Saishi. When creating a Pseudo Zombie a living sacrifice is required for Saishi’s ki to use as a vessel. The process which a human body is converted into an undead vessel is similar to the process of petrification that exists in nature, with certain plants. When a tree or plant becomes petrified, what happens is that over the course of years, the original biological elements of its cells are very gradually replaced by mineral elements so gradually that the infusing minerals take on the same shape and appearance as the original biological cells. In effect, the original biological cells act as a matrix, or as a sort of "molding", for the incoming mineral deposits and what you end up with is a gradual build up of minerals in the exact shape of a tree trunk, or a plant of some sort. This same process, vastly speeded up, is what happens when a human body is transformed into a zombie. Saishi’s energy flows into it and replaces all the original human organic matter but it does it gradually, and in such a way as to mimic the original cell structure. And the organic matter is not completely replaced, but is only 99.9999 percent replaced. A tiny amount of the original human cellular matter remains as a template, spread molecularly thin throughout the newly generated, unnatural tissue which is made up of necromantic energy in more or less solid form. The original soul attached to that body loses its adhesion and undergoes the metaphysical equivalent of evaporation into the ether. The user can theoretically reincarnate a limitless number of people in this way, so long as they have enough sacrifices, and energy to perform the technique.. The reason I call them Pseudo Zombies is that the are less the walking undead and more like puppets their personalities are merely projections of Saishi’s and while this does provide them some degree of free will they are little more then mindless killing machines under her command. Though they can’t regenerate unless aided by an outside source their bodies will always revive are able to keep functioning even if their heads are grievously damaged. Infact injuring them releases quickens the flow of ki in their body making them stronger. Since the ki sustaining their bodies is tied to the wood element the Zombies have unlimited reserves of energy, as well as seemingly near-unlimited stamina and can fight continuously. The only way to kill these Zombies is to completely obliterate them in one shot so that they don’t have time or the resources to revive.

True Zombie
This was the technique used to ressurect Saisei (Gozen Tomoe). It redirects the flow of KI back into the dead re-linking the soul, thus giving them life again. The process also reverses the subject’s age to its prime. The subject is effectively immortal. Once the process is complete they will not age beyond their prime. The cells of;their body are not alive, and are not subject to cellular mitosis, which usually accompanies growth in normal human organisms. Since the subject isn't technically "alive", they are also immune to all known Earthly diseases and infections. While a powerful and versitile technique it has number of limitations. The main one is that it can only be done before the soul has passed on which leaves a short window to prepare. Also the body must be intact, which is why  Oda Nobunaga’s soul was transferred to another body. His head was chopped off and his body was burned he couldn’t be made into a zombie even though the Mibu were on hand. Finally while Zombies are unaging their bodies heal at a normal human rate. The reason Tomoe Gozen is considered a zombie but Taihaku isn’t, because the technique was perform on him by the Former Crimson King while he was still alive. While it was performed on her by Saishi after her death. While Saisei is subject to Saishi’s will she does have free will. I though that was one of the funnest moments in the series was Saisei in her nurse’s outfit doing cutesy poses and looking absolutely miserable.

Specters
Specters are the resurrected dead brought back to life. The technique eliminates the main weakness of true zombies in that it can reincarnate souls that have already passed on. This technique is a variation of the Pseudo-Zombie technique where a sacrifice is required for the soul of the reincarnated to use as a vessel. However this sacrifice does not need to be living. Dust and ash encase the sacrifice body, giving them the same appearance that the reincarnated had at the time of their death. The reincarnated body will appear grey and in a state of minor decay, marred by cracks and other imperfections, they also retain their memories, and all abilities they had in life. As a downside, the reincarnated seem to retain any permanent body damage and physical limitations they received during their lifetime. The reincarnated all have black sclera and white irides. While Specters retain all of the memories and abilities of their personalities are completely eliminated, turning them into mindless killing machines under summoners command. This makes them less effective as warriors and as soldiers. Specters don’t have auras so other than sight, there’s no other way to know their position. This technique can also be used to to resurrect inanimate objects. The user uses their ki to materialize a vessel by which the soul of the object can enter, however only the weapons of those who have learned to talk to them can be resurrected.

Trivia
This technique can be compared to Naruto's Summoning: Impure World Reincarnation