Siren Deep

 is one of the protagonists in Rainbow PoP! Pretty Cure! and its sequel, Rainbow PoP! Pretty Cure! Spectrum Sparkle!. Siren is the Student Council Secretary of Colorete Academy. When you look and meet Siren, she is quiet. She is strict. She was smartest. Being she was excellent at all subjects. She was seems as she wants to do her achievements. Siren has simple and good looks, as she looks like a nerd. She can concilling and solving some problems.

Her pretty Cure ego is Cure Cobalt, the color of Wisdom, holds the power of Water.

Cure Cobalt
Kyua Kobaruto (キュアコバルト) is the pretty Cure form of Siren. She represents the color of Wisdom, holds the power of Water.

Transformation
Let's Go! Pretty Cure! Rainbow Sparkle! PoP! is Siren's transformation phrase in ''Rainbow PoP! Pretty Cure! and Rainbow PoP! Pretty Cure! Spectrum Sparkle!''.