The fantasy eroge Aiyoku no Eustia was developed by August (Fortune Arterial, Yoake Mae yori Ruri Iro na) and released in Japan on April 28, 2011. The story takes place in Novas Aether - a city that floats in the sky, thanks to the prayers of the holy maiden, after the surface of the world broke down. Years ago, an incident called "Grand Fall" occurred, where the holy maiden's prayer became interrupted and a portion of the city fell down, causing a huge cliff to appear in the lower layers of the city. After time, the new bottom layer became the dwelling of all kinds of low-lives and people who lost much of their former lives during the "Grand Fall", and became known as "The Prison". Also, lately a disease which causes people to grow small wings has spread throughout the city, and a unit have been formed to deal with these people swiftly.