Eir Aoi is a Japanese singer from Sapporo, Hokkaido, signed to Sacra Music. After being discovered through the Japanese video sharing website Niconico, Aoi made her major debut in 2011 with the release of her first single "Memoria", whose title track was used as the first ending theme to the 2011 anime television series Fate/Zero.

Fate/Zero is a Japanese light novel written by Gen Urobuchi, illustrated by Takashi Takeuchi, and is a prequel to all routes in Type-Moon's visual novel, Fate/stay night.