Reishi



, sometimes also called Spiritrons are the fundamental particles which make up all spiritual things. These include the spiritual bodies of the hollows and shinigami, and the two planes of existence, Hueco Mundo and the Soul Society in their entirety. Reishi are invisible to mortals (such as humans with the exception of spiritually aware ones such as the Quincies); they can however still interact with normal matter and produce physical effects. It is noted, however, that Spiritrons and atoms do not mix well.

There is a certain amount of Reishi in the human world, too. More free Reishi tend to be found in places closer to nature. Quincy collect these Reishi to use for combat in the form of Reiryoku.

Reishi in the atmosphere is also able to be controlled freely, allowing a person to gather it under their feet so that they can stand in air.