Shironeko Project

is a free-to-play action RPG developed and published by Colopl for Android and iOS. It was initially released in Japan on July 14, 2014. An English-language version was released internationally under the name Colopl Rune Story and operated from July 23, 2015, to October 7, 2016.[

An anime adaptation of the game's 3rd-anniversary event titled is produced by Project No.9 and premiered on April 6, 2020.

Plot
A long time ago, there is an ancient legend revolving around two figures, the White Maiden of the Sky; represented by the White Cat, and the Black Prince of Darkness; represented by the Black Cat. At the same time, a war between the demons and the guardians of light took place, with the demons led by the Black King of Darkness attacking the lands in the sky. The Black Prince however, despite the wishes of the Black King, defied his orders and falls in love with the White Maiden, in hopes that their union would end the war. Both were not meant to meet and love each other as the war ravaged the world around the land and the skies.

Several millennia after the war, in a world consisting of numerous isles, a young hero from the Astora Isle encounters the adventurer Kyle and follows him on an expedition on the isle. They meet a mysterious girl named Iris and a talking white cat named Catra, and together they make their way to the isle's ruins, where they find a flying island. Kyle becomes consumed by darkness there, and the party resolves to travel to the ends of the world on the flying island in order to find the seven "Great Runes", following Kyle's words before he disappeared. Upon their adventures towards finding the Runes, both the hero and Iris start to fill the pieces, meeting friends and enemies and discovering their true identities.