Soukyuu no Soleil: Fullmetal Eyes is the third eroge in the "Valkyrie Saga" series developed by SkyFish, following the original Shirogane no Soleil from 2007 and the Gouen no Soleil sequel from 2008. The game plays as a tactical battle sim, with a story that takes place in a world orbited by two moons: one white and the other blue. The humans are constantly fighting magical monsters called "berserk", which are weapons that activate using the souls of humans. Valkyries come from the white moon to aid them in battle. This is where the main protagonist Sora meets the valkyrie Odette on the battlefield, and the two go on to fight alongside one another. The game's release date for Japan is February 25, 2011.