A young Shirou Emiya and his adoptive father Kiritsugu travel to Fuyuki in order to investigate the Sakatsuki family, who are rumored to be harboring a child with powerful magic abilities.

After succumbing to an unenviable fate, Kiritsugu Emiya has left Shirou Emiya the duty to save mankind in his place. The world is dying and time is ticking, but when the salvation Shirou seeks is at the cost of his only family left-his younger sister-will he still have the heart to pursue this duty? Shirou is now pressed with the choice to continue being a hero of justice-or become the very evil his ideal has vowed to vanquish. The orphan is alone once again, yet his body is still made of swords. The Fifth Holy Grail War now begins with his oath under snow.—MAL Rewrite