Reishi is a term used in the anime and manga series Bleach to refer to "spirit particles" or "spiritrons". It is the main component material of souls and all spiritual matter. Reishi is essentially the same as Kishi, which is what objects in the World of the Living are made of. As a result, Reishi most likely has a wide array of elements which make up the term "Reishi" (as in hydrogen, oxygen, sodium, etc) . Quincy, a group of characters in Bleach, use Reishi for all of their techniques. They tear the Reishi out of the environment and combine them with their own Reiryoku to shape it in a certain way. They use their cross as a sort of focal point for the Reishi to easily combine with their Reiryoku, and then be shaped into a weapon. Shinigami, another group of characters in Bleach, entirely rely on their Reiryoku, which is an inner source of power, and make no distinction between Reishi and Reiryoku, meaning that they have a limited source of energy compared to the Quincy.