The Secret of the Luna Sphere

The Secret of the Luna Sphere is the 28th episode of Sailor Moon R. It was preceded by Rubeus Strikes Out and followed by Emerald Takes Over.

Plot
Rini is being chased by Prince Diamond's droid, the Grim Man, in her dream, keeping her asleep. Diamond's brother Sapphire thinks that with their Dark Crystal they can win without the Imperium Silver Crystal or Rini, but Diamond, Emerald, and Wiseman disagree.

Luna-P, the Luna Sphere, appears before Serena, Amy, Raye, Lita, Mina, Luna, and Artemis and turns into a crystal ball, where a Sailor Scout named Sailor Pluto talks to them and tells them about the Grim Man. She then sends them into Rini's dream to fight him.

They find Rini, but she does not remember them. The Grim Man appears, and the girls all transform to fight him. They are unable to defeat him, however, and as Rini runs away, Sailor Moon follows her. Rini tells her that her mother is trapped inside Crystal Palace (as the dream is set in Crystal Tokyo). Luna and Artemis tell Sailor Moon that they need her to fight the Grim Man. They arrive at the battle, but Grim Man throws Rini into a hole, where she is saved by Sailor Moon, who then destroys the Grim Man with Moon Scepter Elimination.

They enter Crystal Palace and see Rini's mother, before they all wake up in the present.