Kidō (lit. "Way of the Demon" or "Way of the Spirit"; dubbed "Demon Arts") refers to techniques used by shinigami in which they concentrate their spiritual power into spells of various powers. However, the term has also been used to loosely describe the abilities of Orihime Inoue, whose powers transcend even some of the most advanced kidō spells. These spells serve a number of uses, such as healing, restraining, defending, and attacking. Certain zanpakutō, categorized as kidō-type zanpakutō, have the natural ability to produce spells or some sort of magical effect.
 Kidō Mechanics
Kidō spells are ranked from 1 to 99 in terms of power and difficulty; the latter being the most powerful but the most difficult to perform. Typically, a shinigami must initially recite an incantation as preparation for whatever spell he/she wishes to use (always followed by the type of kidō and its rank number). On the other hand, there is a more effective method to casting spells without having to recite incantations.
Eishohaki refers to the the technique of using kidō without chanting an incantation. Although it drastically curtails the time used casting a spell, it also significantly weakens the effect the spell would have as opposed to if an incantation was chanted. While any shinigami competent in kidō can use this technique, its effectiveness is largely contingent on one's the skill level, otherwise the spell may fail to work. As such, the technique is generally only used by shinigami officers, who are well versed in kidō.
The prowess of a kidō spell is mostly dependent on the power of the shinigami using it, as even a weak spell is capable of causing devastating effects if used by a high level shinigami.
 Main Kidō Types
In total, there are 3 main kidō types.
- Bakudō (Binding Spells): A broad category of defensive spells used to block or repel attacks as well as restrain enemies
- Hadō (Destructive Spells): Offensive spells which are used to harm a foe.
- Healing Spells: As the name implies, the purpose of these spells is to heal targets. They require no incantations, nor are they named or ranked. To perform a healing spell, the user simply places his/her hands over the wound as their hands glow green with spiritual energy, thus proceeding with the treatment.
 Kidō in Combat
Even though kidō can be very advantageous in combat, the nature by which it is used makes it something that can only be practically used by skilled shinigami. This is because reciting incantations and other preparations inconvenience the user by leaving him/her vulnerable to enemy attack, which against more formidable opponents, can have fatal results. Nevertheless, adept shinigami such as Rukia Kuchiki have managed to work around such drawbacks by creating distractions, giving them adequate time to complete the requisites. Other methods used to counteract the downsides include the aforementioned Eishohaki and what is known as a Double Incantation, which involves mixing the incantations of two or more kidō spells to baffle the enemy and conserve time. The latter technique is a mark of a shinigami who is exceptionally skilled in using kidō, although it more or less serves a a replacement to the aforementioned technique for those who are not powerful enough to use it productively. A rarer form of the double incantation is mixing both Bakudō and Hadō incantations, which is even harder to produce. Kidō is mainly used for preemptive attacks rather than direct combat and are most efficient when the opponent can't see it coming. Members of the Kidō Corps also excel in the use of kidō in combat situations, abandoning the use of weapons.