Rachel Bennett (Rikka Hishikawa in the original Japanese version) stands as a central character in the series. This 14-year-old serves as her middle school's student council secretary. Academically gifted, she consistently ranks within the top ten in national mock exams and holds the top position in her class, though her scores later dip slightly due to commitments to competitive spelling bees and similar activities.

Her appearance features dark blue eyes and dark blue hair, typically worn loose with small braids tied back by a pale blue ribbon. She occasionally wears red glasses. Her standard attire consists of a white long-sleeved blouse with a blue bow tie, a light blue pleated dress with navy details, black socks, and short brown boots. During summer, she switches to a white and blue sailor-style dress with light blue accents, paired with dark blue shoes and white socks.

Rachel is intelligent, calm, and responsible, yet unafraid to voice her opinions. She takes pride in her intellect and enjoys studying. She often finds herself managing the impulsive behavior of her childhood friend, Maya, despite preferring a quiet, drama-free school life. Her loyalty to Maya stems from their long history; friends since elementary school and neighbors, Rachel frequently recalls Maya protecting her during childhood, fostering deep trust. She is also childhood friends with Clara Yotsuba.

Her family includes a mother working late shifts at a local hospital and a father traveling globally as a photographer. Rachel maintains contact with her father through letters.

After encountering a mysterious merchant, Rachel receives a Glitter Charm. She later uses it to transform into Glitter Diamond to support Maya and the team. Her transformation begins with her pixie partner, Rory, calling out. She places her Glitter Charm onto Rory’s silver heart medallion, shouts "Glitter Force Makeover!", and spells "L-O-V-E" on her Glitter Pad. During the transformation, her body glows blue, her hair lengthens into a light indigo ponytail, and she dons a feathery blue-and-white costume with diamond earrings, a gold choker, and matching bracelets and boots.

As Glitter Diamond, she represents wisdom and commands ice-based powers. Her signature introduction is, "The light of Wisdom! Glitter Diamond!" Her solo attacks include "Twinkle Diamond" (requiring her Glitter Pad and Charm) and "Diamond Shower" (using her Glitter Heart Arrow and Charm). She participates in group attacks like "Togetherness Power Arrow" (with Glitter Heart, Clover, and Spade) and "Five of a Kind Glitter Bow" (with the full team).

Key relationships feature her role as Maya’s steadfast friend and occasional stabilizer. She initially feels jealousy toward Mackenzie due to Mackenzie's closeness with Maya, but this evolves into a solid friendship. Her partnership with Rory enables her transformations; Rory’s crush on her sometimes causes embarrassment. A notable subplot involves her discovering Ira unconscious on a beach; she shelters him and defies Glitter Ace to protect him, leading Ira to reciprocate by shielding her from dangers later. This establishes a complex, rivalry-tinged bond between them.

Trivia notes her birthday on September 17 (Virgo), revealed via an official interview. She is the only Glitter Force member without a confirmed last name in the English adaptation. Episodes focusing on her character development, such as one centered on a karuta competition, were cut from the English release.

Etymologically, her Japanese surname "Hishikawa" combines "hishi" (diamond shape) and "kawa" (river), while her given name "Rikka" means "snow" (from the kanji for "six" and "flower"). The name "Rachel" derives from Hebrew, meaning "ewe" or "one with purity".