Rikka Hishikawa (Rosalina Hopkins in Glitter Knights and Rachel in the canon Glitter Force Doki Doki) is one of the main characters in Doki Doki Pretty Cure.
Rikka has navy eyes and darker colored hair worn loose with a small braid, one on each side of her head pulled back and held together at the center. Her bangs are kept short with two thin forelocks that reach her chest. Her casual outfit is a light blue pleat dress with blue accenting and white frills, worn over a white blouse that has a navy bow-tie. She wears plain brown shoes with dark blue socks. In summer she switches to a white tunic reminiscent of a light blue sailor top that has a sapphire ribbon at the chest to match the light blue diamond pattern tracing the bottom. It is worn with a pale blue pleat skirt, blue shoes, and white socks. She sometimes wears red glasses.
As Cure Diamond, Rikka's eyes become brighter while her hair grows in length and turns pale indigo. Her hair is worn in a thick, high ponytail with a curl on the end to match the four separate curls hanging from it, two of which are thicker than the others. Her bangs are brushed neatly and she gains two more forelocks. She wears blue diamond shaped earrings a small, ice-blue brim on her head, lined in dark blue to match the diamond in the center, lined with feathery white material. Her ice-blue dress appears shorter in front than the back with a pale blue feathery material around the bottom of the skirt and the shoulders. Around the torso is dark blue and white lining, along with a dark blue heart-shaped ornament attached to a white border and cloth, along with a light blue bow sewn to the right. Her skirt is shaped to reveal a layered skirt beneath it. Comes with white shoes with a loose, pale blue cuff and a thin yellow band around the ankle, where a small white flap is located. On each wrist is a yellow bracelet to match her choker. On her right side, hangs her Lovely Commune.
Rikka is a quiet, honest, blunt, not afraid to speak her mind and a very intelligent girl. She is a second year student at Oogai First Middle School, and the student council's secretary. She loves to study, and is a genius at it, being one of the Top 10 scorers in the national trial exams. She is great at observing people and situations. Rikka is at the top of the class and constantly placed as the first place in her school, however her scores started to drop as she was in second place because of starting to play competitive karuta.
Rikka is childhood friends with Mana, since they live near each other. Ever since they were children, Rikka has been taking on the responsibility of looking after the troublemaker Mana, sometimes being taken advantage of. Despite that, she also was always protected by Mana which makes Rikka trust her. She strives to lead a quiet school life, but is often dragged into various things by Mana.