According to Nasu, Fate/EXTRA is a JRPG which takes place set in an alternate universe that split from the Fate/stay night timeline in the 1980s to 1990s. The Story is set in the in a school called Tsukumihara Academy, a fictional place existing with an artificial environment called the Moon Cell. There, the Moon Cell orchestrates a replication of the Holy Grail War using a system called Serial Phantasm or SE.RA.PH, which handles the summoning of Servants. Servant data is taken from the Automaton (Moon Cell Automaton), a spiritual computer system built on the lunar surface by a pre-human civilization and discovered by humans in the year 2032. The Automaton has monitored and recorded all occurrences on the Earth (including the activities of human heroes) since time immemorial. In this sense, it is similar to the Throne of Heroes, but it's possible to summons beings which aren't present in the Throne. Each of the 128 participants in the war must duel the other Masters in a place called the Arena, where failure results in deletion from both the real and digital worlds. When only one remains, the "Holy Grail" shall grant the victor's wish.

The Moon Cell Automaton is a spiritron computer, which exists on the moon and has the power to grant any wish. All across the spiritron-constructed virtual world, SE.RA.PH, Servants and the Masters who control them fight for the right to be the Moon Cell Automaton’s one owner in a ceremonial conflict known as the Holy Grail War. Now, the Servant Nero Claudius and her Master have won the Holy Grail War and have obtained the universal wishing mechanism, the Holy Grail. They also obtained the Regalia, a ring that proves their kingship. With it, they rule over their once-enemy Servants and start a new beginning on the moon’s new world. But a new enemy has appeared before them. And this enemy has something that shouldn’t exist: another Regalia. [From [url=http://www.xseedgames.com/games/fateextella-the-umbral-star/]official English site[/url]] Fate/Extella: The Umbral Star is the newest installment to the Fate series of games/anime. Developed by Marvelous and co-published by Marvelous and XSeed. This is an action hack and slash game with RPG elements.