Rei (レイ) is a lingering spirit (otherwise known as a Stand), who appeared in the Ghost Ryokan Arc. She is currently employed by Oiwa in Senboukyou, a hotsprings bathhouse where souls of the dead receive help to move on to the other world.
She appears as any other lingering spirit, white, gray and semi-transparent. She has long, dark hair that usually covers the left half of her face. Rei is usually seen wearing a white yukata and a hitaikakushi on the top of her head.
Rei is kindhearted and has a sense of righteousness, as seen when she tried to tell Oiwa that both her and the Senboukyou had changed, in the sense that Oiwa had gone on the wrong path by not letting the lingering spirits move on. Rei seems to be fairly perceptive, as she could see that Sakata Gintoki had the potential of a stand-user to rival that of the Okami. She was also the first to notice that Tagosaku in his final form was sucking in the stands of all the living things in the surrounding area. Rei also seems to have a sense of humor, e.g. when she joked about washing Gintoki's back.
As a child and an orphan, Rei was taken in by Oiwa, who employed her in Senboukyou to help take care of lingering souls before they passed on. Later on, Rei herself would die and become a lingering spirit, however it is uncertain how or why her death happened.
With help from Sakata Gintoki of the Yorozuya, Rei would later turn against Oiwa and revolt when Oiwa purposely wouldn't let the lingering spirits move on. However, Oiwa came to realize her wrongdoings, and Rei then decided she did not want to achieve enlightenment, but would rather stay behind with the living Oiwa to help run the onsen. However, Rei joked that she chose to stay behind because there was a certain man (Gintoki) whose back she wanted to wash.
In the manga, when Oiwa was alone, she stayed with her.
- Rei has the same voice actress as Allen Walker from D.Gray-man and Mine from Karneval.