Singularity F: Flame Contaminated City, Fuyuki
Disaster strikes Chaldea, the Security Organization for the Preservation of Humanity.
A lone Master is thrown into Fuyuki during the year 2004, where a Holy Grail War is raging.
The journey to reclaim human history begins in a desolate, burning city.
The tutorial singularity in Fate/Grand Order. Technically the first singularity, but isn't numbered as such as it serves as a prologue, instead being known as Singularity F. It's set in the year 2004 in the Japanese town of Fuyuki, where a certain holy grail war has ended in disaster. It was adapted into the film Fate/Grand Order: First Order.