Sella (セラ, Sera?) is a caretaker of the Einzbern household Illya's World in Fate/kaleid liner PRISMA☆ILLYA. Along with Leystritt, she watches over Illyasviel von Einzbern and Shirou Emiya while Irisviel and Kiritsugu travel.
After Irisviel and Kiritsugu worked together to stop the 4th Fuyuki Holy Grail War, they moved to an house in Fuyuki City with their daughter Illya and their adopted son Shirou. They also brought Sella and Leysritt from the fallen Einzbern family so that they act as Illya and Shirou's guardians when they are overseas.
Along with Leysritt, they wear the same casual clothing that was first represented in Character material with details about their normal lives.
Contrary to Leysritt, Sella seems take her house duty work very seriously, even putting her original maid outfit when Illya's friends were visiting the Einzbern residence. She is shown to act tough with Shirou, often claiming that since he is the eldest son of the house, he has to take his responsibilities.
Fate/kaleid liner PRISMA☆ILLYA Edit
While it is unknown if Sella has the same abilities as her original counterpart, it is hinted that she's capable in hand combat such as when she spars with Leysritt.
As a caretaker, she is able to do various household skills such as cleaning, nursing, and cooking.