Luna Inverse is the Knight of Ceifeed and the older sister of Lina Inverse. She is two years older than Lina.
As the Knight of Ceifeed, Luna wields an immense amount of holy power. She can cut a Dragon Slave in half, and once defeated a plasma dragon with a kitchen knife. Luna was the dragon priestess Filia Ul Copt's first choice to save the world from the prophecy of destruction though Luna thought Lina was a better candidate for saving the world from the prophecy of destruction. Luna is more or less equal in power to, if perhaps somewhat stronger than her uncle Xelloss. It is not made entirely clear whether or not Luna is more powerful than Lina. Although Lina is plainly terrified of her older sister, during TRY, Luna currently works part-time as a waitress in her hometown of Zephilia.
Her father is an ex-mercenary and her mother is an ex-sorceress. It is unknown if she is aware of her father’s real identity as Enma Meioh but it is hinted that she might.
Luna and Lina's relationship is not the most affectionate, to say the least (although Lina surprisingly calls her onee-chan, with the suffix -chan usually denoting close friendship or affection). Apparently, when they were younger, Lina would misbehave and Luna would "punish" her. (The most notorious incident between the two was when Lina set up a device that projected an image of Luna while she was taking a bath and sold it to lecherous boys). These punishments are probably why Lina is so terrified of Luna. This is further noted when Lina manages to suppress the pain of anti-magic circlet's electrical shock in order to cast a spell, noting "Compared to what my big sister used to put me through, that was a piece of cake!" Luna also has a surprising amount of control over Lina. All it took was a simple letter saying "Shut up and do it- your big sister" to get Lina to agree to help Filia save the world from the prophecy of destruction - although this was after Lina had a panic attack upon receiving the letter, prompting her to quickly build and seal herself inside a coffin, in a large pyramid.
One day, Luna met and befriended the half-troll, half-beastman Dilgear (a former servant of her sister's traveling companion; Zelgadiss Graywords and his great-grandfather; Rezo the Red Priest) when he was wandering around looking for food. She took him in and kept him as a pet, renaming him "Spot".