Arpeggio of Blue Steel (蒼き鋼のアルペジオ, Aoki Hagane no Arpeggio) is a Japanese manga series produced by Ark Performance and serialized in Shōnen Gahosha's Young King Ours. Seventeen manga volumes have been released and an anime series by Sanzigen aired from October 7, 2013, to December 23, 2013. The same studio also produced two films based on the series. The first film was released on January 31, 2015, while the second film was released on October 3, 2015. Due to global warming and rising sea levels in the early 21st century, much of Earth's landmass has been lost. In 2039, fleets of powerful sentient warships, armed with advanced technology and possibly 'alien' weaponry, mysteriously appear and devastate the world's naval forces. These ships, collectively called as 'The Fleet of Fog', impose a worldwide naval and aerial blockade, preventing humanity from both traveling the oceans and to other nations. During the blockade, the Fleet of Fog created Mental Models, humanoid avatars containing a ship's Union core, as a means to develop self cultivation and to overcome their lack of creative thinking of tactics that humans possessed, which at the same time made the Mental Models develop their own unique personality.