The important difference between kagura and norito or mikë is that it is possible to fail to perform kagura. Once a norito has been written, it is simply a matter of reading it off a sheet of paper, as shinshoku do not memorise most norito. It is theoretically possible to fail to read the norito, but that’s not a possibility it makes sense to include in the game. Similarly, once mikë has been selected, it is simply a matter of offering it to the kami. It is true that some mikë might be difficult to make, in which case it could be similar to kagura, but most mikë is simply harvested and offered as it comes. Kagura, on the other hand, must be performed, and it is not trivial to do so. Personae can only include kagura in a matsuri if they have someone capable of performing it.
There are a number of standard kagura. These are normally performed by miko, and require one or more performers. No creativity is required to add these to a matsuri, but doing so should still provide a benefit, because the personae do need to have trained dancers available. Let us say that adding standard kagura performed by a single dancer provides +1 die to roll when determining whether the kami responds to the request.
Kagura normally requires music as well as dance. The music can be as simple as a drum beat, or involve as many as half a dozen musicians. For standard kagura, the music can be provided by a recording, but if the personae have created new kagura for the matsuri, they need musicians as well as dancers. Each part of the kagura has a performance difficulty, and the easiest kagura have a difficulty of 4, meaning that they can be performed by someone with minimal training. The different parts of kagura can have different difficulties, although in standard kagura all the dance parts are the same. So, any piece of kagura involves a number of parts, each with a difficulty.
The base is that kagura with a single part of difficulty 4 adds 1 step to the effect of the matsuri. No creation process is required, because the standard kagura is simply added to the matsuri in the standard slot. If there are more people involved in the kagura, it gives a larger bonus. Two people allows a 1-step increase, while four allows 2 steps, eight allows 3, and thirteen allows 4. Beyond that, there are no direct bonuses. (Why thirteen, rather than sixteen? Because there is a traditional large-scale kagura involving eight dancers and five musicians.)
Adding steps to the kagura by designing a new kagura follows the same rules as for adding steps to norito and mikë, with an addition to take account of the difficulty of the resulting kagura. The creator may add one to the current total for creating the kagura by adding three to the difficulty of any one performer of the kagura. This should be done last, after all possible revisions have been completed, but it allows difficult kagura to have large effects. So, if the kagura requires eight people, the creator can increase the total by 8 points by giving each part a difficulty of 7. If the kagura includes a dance with eight identical parts, adding 3 to the difficulty of the dance adds 8 points to the total, because each of the eight dancers must be able to meet the new difficulty.
If any of the performers fail their roll, the kagura fails, and the matsuri loses the benefits of the kagura, although it retains the benefits of the norito and mikë. To avoid this possibility, performers can learn a particular kagura, which allows them to perform it with no chance of failure. This is only sensible for a standard kagura, one that will be used repeatedly, because learning the kagura takes time and effort. Just how much time and effort, however, is something to determine a bit later.