A car screams down the moonlit streets of Fuyuki City, with a very happy-go-lucky Irisviel behind the wheel and a slightly unnerved Saber sitting next to her. The evening takes a bad turn when a mysterious shadow darts in front of them. The person claims to be Saber's loyal retainer, yet Saber has no memory of them...

The rules of the game have changed and the Masters have a chance to earn an extra command spell. All they have to do is find Castor and kill him.

Battle rages throughout Einzbern Castle: Kayneth's magical mercury sphere versus Kiritsugu's formidable gun arsenal, Saber and Lancer join forces against Caster in the forest, and Irisviel detects a new enemy as she and Maiya make their escape.

With rules being broken and new players entering the tournament, the remaining Heroes and Masters are entering a new phase of the tournament. What Tokiomi does next will affect everyone.

Saber vs. Berserker, Archer vs. Rider, another hero will fall and a secret will be revealed.

As commanded by Kiritsugu, Saber unleashes her Noble Phantasm on the Holy Grail, with a completely unexpected result. Who will end up winning the war?