Dumble was a Droid belonging to Koan which appeared in episode 63. After Koan found out the Hikawa Shrine was a Crystal Point, she and Dumble disguised themselves as participants in Protect Esthe and flooded the shrine with Dark Power. The disguised Dumble began to attack the others at the class, and as the Dark Power spread the participants also began to fight amongst each other. Rei sensed something was amiss and protected her grandfather from the Droid when Dumble dropped her disguise, and was saved by Sailor Moon's arrival. With the help of Tuxedo Mask, Sailor Moon destroyed Dumble with Moon Princess Halation.

Dumble possessed great strength and fighting skills, and could also generate electric energy waves that immobilized her targets. She also performed a joint attack with Koan called Koan Dark Power Flip. Dumble's seiyuu was Hiroko Emori.