The Boule Brothers, Chiral and Achiral (known as Doom and Gloom in the English dub), are two minor antagonists belonging to the Black Moon Clan. They are under the service of Green Esmeraude, even appearing on her page in the Materials Collection art book. They are more significant in the manga plot, in the anime they are simply monsters of the day.

In the manga, the brothers are sent to greet the Sailor Senshi when they arrive in Crystal Tokyo. They create a mirror-image replica of the Crystal Palace as a trap. When Sailor Moon attacks them, she is paralyzed by a magnetic field from a man-made crystal at her feet. However, Tuxedo Mask destroys the crystal by willing it to break, and the brothers are killed by him and Sailor Venus.

In the anime, the brothers' are used to grow "Dark Henges" at Juuban Park and Juuban Elementary School. They cause all of the pupils and teachers at the school to fight each other, viciously and constantly. They also attack Chibiusa's best friend, Momoko, which causes Chibiusa to reveal her identity as "The Rabbit" to the Black Moon Clan.