Immortals: Muv-Luv Alternative is a mobile game from the "Muv-luv" series, released on both iOS and Android exclusively in Japan. The setting of the game inherits the worldview and the story background of the original work "Muv-luv", which is a visual novel of love comedy in the first chapter, then becomes a serious sci-fi adventure story. Players need to control the popular characters from the series and Tactical Surface Fighters (TSF), a kind of large bipedal machine, to fight against a mysterious swarm of alien creatures called "Beta", as they have invaded and disrupted the Earth. All the stories narrated in the game are completely new and original. Players can enjoy a riveting plot with an intense atmosphere and charismatic characters.

This is the story of a battle in countless probability-time and space-time. Running a humanoid weapon called tactical walking fighter (tactical aircraft), Humanity is fighting against the extraterrestrial species "Beta", one of such parallel worlds "a.d. 2008, modern". Emergence of alien origin species in Yokohama, Sado Island, and Ogura - silence was broken and the tragedy came to an end again. With the investment of influential people around the world, I was established by PMC (Private Military Company) Immortals, serve as a tactical manager to regain Yokohama where the hive appeared.