Aisha Greyrat is the daughter of Paul Greyrat and Lilia Greyrat, born from their affair during Paul’s marriage to Zenith Greyrat. As an illegitimate child, she develops an inferiority complex, particularly in relation to her half-sister Norn Greyrat, whom she perceives as receiving preferential treatment. Raised primarily by her mother, Aisha undergoes strict training from birth to become a maid for her older half-brother, Rudeus Greyrat. When she is four years old, the Fittoa Region Teleport Incident transports her and Lilia to the Kingdom of Shirone, where they are held captive until Rudeus rescues them. Witnessing his abilities firsthand, she willingly chooses to serve him as his maid.

Aisha is extraordinarily intelligent, mature beyond her years, and possesses a sharp, analytical mind. Her personality blends a playful, sometimes mischievous demeanor with a pragmatic, cunning, and manipulative streak. She excels at virtually anything she attempts, from academics and magic to housework and leadership, though she can struggle to empathize with those less capable. She harbors a notable brother complex toward Rudeus, often making suggestive comments and showing little modesty around him. She enjoys gardening and successfully cultivates rice in an effort to recreate Rudeus’s favorite Japanese food. By age ten, she achieves Elementary rank in all six basic magic types and the Elementary rank in the Water God Style of swordsmanship.

Aisha’s role evolves from a devoted maid to a key figure in the Greyrat family’s operations, becoming the effective leader and strategist for the Rude Mercenary Company and transforming it into a powerful transcontinental organization. The powerful being Perugius Dola holds her in high regard. Her relationship with her half-sister Norn is tense for many years but begins to improve after Norn has a child. Later in life, a genuine romantic relationship develops between Aisha and Rudeus’s eldest son, Ars Greyrat. They are discovered together, elope, and Aisha becomes pregnant with a son named Leroy Greyrat. The event causes a rift with Rudeus, leading Aisha to leave the family home before eventually reconciling under specific conditions set by Rudeus.