Rent Fate Stay Night: Vol.6 (2006)

The mysterious eighth Servant attacks, seeking to dominate Saber in order to claim her as his own. How will Shirou protect her? If they should ever win and obtain the grail, Shirou and Saber would still have to choose between their own conflicted feelings and their self-imposed obligations, but will they ever have that chance? Meanwhile, another figure lurks in the shadows biding their time for when they can once again make an attempt for the elusive grail! Contains Episodes 21-24.