Rei

Rei is reserved and initially resigned to her existence at Senbokyo. She has spent long enough under Oiwa's authority to understand both the inn and the ghosts inhabiting it.

She nevertheless possesses a strong sense of right and wrong. When Oiwa's behavior becomes intolerable, Rei openly tells her that what she is doing is wrong and joins Sakata Gintoki in rebellion.

Rei also develops an affectionate attachment to Gintoki. Even after being given an opportunity to move on, she finds a reason to remain in the earthly world connected to him.

As a ghost, Rei exists as a supernatural spirit rather than a living human. She can interact with other spirits and operate within the Stand-filled environment of Senbokyo.

She is knowledgeable about the supernatural rules governing the inn and therefore becomes particularly valuable to Gintoki once he begins resisting Oiwa.

Her effectiveness is based more on her knowledge and spiritual nature than on elaborate combat techniques.

Rei appears after Gintoki, Shinpachi, Kagura and Tae travel to Senbokyo for a hot-spring vacation. The supposedly relaxing resort is populated by ghosts and controlled by Oiwa.

Gintoki is forced to work at the inn and eventually reaches his limit. Rei joins him in rebelling against Oiwa, and the pair recruit several historical ghosts—including Oda Nobunaga, Mitsuhide Akechi and Hideyoshi Toyotomi—for assistance.

After the conflict is resolved, Rei appears capable of passing on, but later returns to Senbokyo because she feels she still has something left to do in the world. She admits that there is a particular man's back she wants to wash.

Oiwa is Rei's employer at Senbokyo and the person against whom she eventually rebels.

Sakata Gintoki becomes Rei's principal ally during the Senbokyo incident. Rei later returns after apparently moving on because of her lingering attachment to him.

Tagosaku is the powerful Stand associated with Oiwa and a major obstacle during Rei and Gintoki's rebellion.

Oda Nobunaga, Mitsuhide Akechi and Hideyoshi Toyotomi are ghosts recruited into Rei and Gintoki's plan.