Miyara Sayaka| Cure Music

A mysterious girl who works for the Dusk Kingdom, who goes by the name of Black Sound. Though she's not evil, she lives there to hunt for the cures. Chaoko and her friends sense something in her. Chaoko revealed she's the 6th Pretty Cure on the team. Sayaka is shy and doesn't want to harm the cures, but is threatened by Frost, Ivy, and Boulder to do as they say or else. As she did her missions she befriended the cures, especially Junko and Ayano seeing this she wanted to leave the Dusk Kingdom because the Pretty Cure treat her better then them, only to be brainwashed and become evil. 

However, Kira was able to snap her out of it and unlock her Pretty Cure power and become Cure Music. Once she accepted her choice she asked Ayano and her friends if she can join the Pretty Cure, which they accept. With the fairies magic, Sayaka became the cousin and stayed over at Ayano's place. Later in the series, she is revealed to be from the Dream Kingdom.