Diana Cavendish is a young witch with pale skin, light blue eyes, and platinum blonde hair accented with tea-green highlights and side-swept bangs. She is widely regarded as very beautiful. Her Luna Nova uniform consists of the standard witch tunic, hat, stockings, and shoes, distinguished by blue accents on her sash, hatband, and footwear. Early concept art depicted her with yellow-blonde hair and pale yellow highlights.

Diana is serious, composed, and highly intelligent, with a deep respect for magical tradition and history befitting her prestigious lineage. Her excellence stems not only from her heritage but also from exceptional self-discipline and maturity. Though often perceived as aloof or condescending, she is genuinely considerate and dependable, correcting others out of concern rather than malice and willingly offering help when asked.

Initially at odds with Akko due to their opposing views on magic, Diana secretly admired Shiny Chariot despite publicly dismissing her. Over time, Akko’s sincerity helps Diana confront her own insecurities, leading to mutual understanding and friendship. Diana possesses a strong sense of duty and integrity, readily accepting blame, refusing unearned credit, and even preparing to sacrifice her own happiness to preserve her family’s legacy.

Born into a 1,500-year-old magical family, Diana possesses extraordinary innate talent, though her magic was suppressed in childhood due to the effects of Dream Fuel Spirit. Through relentless dedication, she becomes the most skilled student at Luna Nova. She excels in advanced magic, including Nullification Spells, Fusion Magic, powerful illusions, water summoning, plant rejuvenation, and advanced transformations.

Diana is also proficient in astrology, object control, healing magic, and magical history, and she demonstrates exceptional broom-riding skill. Her versatility, precision, and depth of knowledge mark her as one of the most accomplished witches of her generation.