Due to the anomalous battle taking place in the desert between Archer and Lancer, various factions become aware of the commencement of the Holy Grail War. As the situation unfolds into chaos, Faldeus, tirelessly acquiring information and manipulating the press, catches sight of a girl new to Snowfield. This girl is Ayaka Sajyou, who wanders the city aimlessly. A mark resembling a Command Spell is engraved on her body.

Following the uproar at the opera house, Saber and Ayaka are detained by the Snowfield Police Department. Saber answers the police’s questioning candidly, showing no regard for maintaining the secrecy of the Holy Grail War. As Orlando expresses exasperation in dealing with Saber and the fallout he is causing, Orlando is visited by a certain man—Hansa Cervantes, a priest dispatched by the Holy Church as Overseer in this fake Holy Grail War.

Clan Calatin finds itself in dire straits after interference from Assassin's Master, Jester Karture. Hansa intervenes, taking up arms not as the Overseer of the Holy Grail War, but as an Executor hunting Dead Apostles. With the Servants dismissed from the stage, the two men clash in a battle fought without Heroic Spirits.

The sun has risen, closing the curtains on the night of the battle at the police station. Orlando, busy with caring for the aftermath of the battle, is visited by Francesca. He fails to conceal his frustration towards Francesca’s flippant attitude. Suddenly, a single arrow soars past them, aimed at Gilgamesh and Tiné who are positioned at the Crystal Hill. After intercepting the second arrow fired shortly thereafter, Gilgamesh and Tiné proceed toward the canyon where they discover another Archer waiting for them.

Shortly before the battle in the canyon, in a mansion situated in a swamp, a lone mercenary attempted to summon a Servant. His codename is Sigma. He holds no desires for this world, nor any intention of leaving anything behind. Chosen by the fake Holy Grail for this empty shell of a man was a Servant so singularly unique that it could never be summoned in a normal Holy Grail War...

After leaving the detention center, Saber and Ayaka wander through Snowfield in search of allies. Before long, the two entered a forest made home by Lancer, the Servant who recently engaged in a spectacular battle against Archer. Challenged to prove his prowess and determine whether they would make suitable allies, Saber unleashes his Noble Phantasm as Lionheart.