Prince Dimande, known as Prince Diamond in the English dub, is the leader of Planet Nemesis in the 30th century. Born on a planet inhabited by prisoners, Dimande initially aims to reason with Neo-Queen Serenity, explaining that he and his people are descendants of criminals, not actual criminals. However, Wiseman gradually manipulates the young prince, turning him against the people of Earth. During an attack on Crystal Tokyo, Prince Dimande sees Neo-Queen Serenity and falls in love with her, fascinated by the anger in her eyes during their brief encounter.
In all versions of Sailor Moon, including the musicals, Demand's intense obsession with Neo-Queen Serenity drives him to kidnap her past self and attempt to brainwash her using his third eye to make her his queen. In the anime, Sailor Moon is saved from Prince Demand's castle by Tuxedo Mask. In the manga, she rescues herself along with Ami, Rei, and Makoto.
The final moments of Prince Demand differ across the series' versions.
In the manga, he is killed by Sailor Moon and Tuxedo Mask after attempting to merge the Silver Crystals of the future and present in a fit of madness upon realizing he was manipulated by Wiseman.
In the anime, Demand sacrifices his life to protect Sailor Moon by blocking an attack directed at her by Wiseman. (In the English dub, he claims he protected Sailor Moon because of his love for her.)
