Rua Nakamachi is a 17-year-old second-year student at Koganei Chuo Private High School and a member of the idol unit Cream Anmitsu, performing alongside her twin sister Nua Nakamachi and Chiko Sekino. Born on January 1, she shares her birthday with Nua. The surname Nakamachi translates to "middle town," reflecting Koganei City district naming traditions.

She has light blue or cyan hair styled in a ponytail with a ribbon, blue eyes, and stands 1.46 meters tall. Her civilian attire includes a light blue and white checkered jacket over a navy dress skirt, a yellow tie, white pantyhose, and yellow shoes. As an idol, her stage outfits feature white thigh-high socks, a blue skirt, and a yellow necktie.

Rua exhibits a dual-layered personality. Publicly during live performances and television appearances like *Anmitsu Academy*, she displays a cheerful, friendly demeanor that endears her to fans. Privately, she reveals a sadistic inclination, deriving pleasure from others' suffering—particularly her sister Nua's. She deliberately exacerbates Nua's emotional distress through mockery of failures or insecurities. This private behavior sharply contrasts her public persona, though whether her kindness is a facade or inherent quirk remains ambiguous.

Performing under Cat Productions, Cream Anmitsu holds greater mainstream recognition than rival groups like Fruit Tart. Rua's relationship with her twin defines key dynamics; her verbal provocations and psychological manipulation highlight Nua's masochistic tendencies. Despite their contentious interactions, they maintain a close bond as twins and collaborators within the idol unit.