Hikari Harper

 is one of the new protagonists and was one of the princesses in Rainbow PoP! Pretty Cure! Spectrum Sparkle!. Harper was one of the princesses in Colorful City and was the happiest of the three. She was one of King Spectrum's cousins after they are invaded by Melancholy Hideout. She is sweet, bubbly and childish. She didn't saw people who have a warmer smile. She loves food, animals and something that likes for her. She loves fashion and music. Harper was the most popular in the class.

Her pretty Cure ego is Cure Luster, the color of Stars, holds the power of Stones.

Personality
Harper was one of the princesses in Colorful City and was the happiest of the three. She was one of King Spectrum's cousins after they are invaded by Melancholy Hideout. She is sweet, bubbly and childish. She didn't saw people who have a warmer smile. She loves food, animals and something that likes for her. She loves fashion and music. Harper was the most popular in the class.

Cure Luster
Kyua Rasutā (キュアラスター) is the pretty Cure form of Harper. She represents the color of Stars, holds the power of Stones.

Transformation
Metallic Sensation! Play! is Harper's transformation phrase in ''Rainbow PoP! Pretty Cure! Spectrum Sparkle!''.