Dark Prince is the final boss of Madou Monogatari II, and is the primary antagonist of the early entries in the Puyo Puyo series. His Japanese name is Satan; despite this, he has little in common with the traditional depiction of the King of Hell. The self-proclaimed Prince of Darkness spends most of his time chasing after Arle Nadja and Carbuncle, often donning thinly-veiled disguises to do so.
Dark Prince first appears in Madou Monogatari II at the top of the Ruins of Lyla. He wants to marry Arle, but Arle refuses. He is defeated in the resulting battle, and Arle walks away with his pet Carbuncle. He later appears in the Game Gear version of Madou Monogatari III, disguised as a frog.
Dark Prince is the the final boss of every Compile-made Puyo Puyo game except Puyo Puyo~n. The series tends to play up his more comedic traits. He is absent from Puyo Pop Fever and Fever 2, but returns in 15th Anniversary and remains a recurring character. He is stated to be the creator of "Puyo Hell," but the definition of Puyo Hell is inconsistent. For example, Draco and Arle in the first game, as well as Dark Prince and Ecolo in 20th Anniversary, use Puyo Hell as the in-universe name of the series's puzzle gameplay; however, it is described as a location in other instances.
In the arcade Puyo Puyo, Arle learns the spell Owanimo and travels to the Dark Prince's dwelling. After humorously referring to him as "Santa," Arle defeats the Prince, leaving him to an unknown fate. In Puyo Puyo Tsu, he sits atop a Puyo Puyo challenge tower. If the player earns a certain number of points without continuing, he dons a mask and goes by the name of Masked Prince. Dark Prince battles Arle with a potential honeymoon as the prize, but attempts to force her into it even when he loses. His plan backfires, and he is sent tumbling towards the earth.
In Puyo Puyo Sun, Dark Prince believes that getting a tan will cause girls to pay more attention to him, and thus he enlarges the sun with a device located in his castle. Either Arle or Schezo storm his castle and, after torching him and defeating him in Puyo Puyo, returns the weather to normal. In Puyo Puyo~n, Dark Prince accidentally unseals Doppelganger Arle, who takes control of him.
Dark Prince reveals himself before the last stage of the GBA Puyo Pop. After losing to Arle yet again, he reveals that the runes that she had been collecting were actually pieces of a hot springs ticket. Arle tosses the ticket away and leaves. Dark Prince does not play another major role in the series until 20th Anniversary. He is possessed by Ecolo, and two characters of the player's choosing battle the villainous duo in the game's final battle.