Fate/stay night [Heaven’s Feel] III. spring song

en years after the Holy Grail War—a battle waged by Masters and Servants over the wish-granting container, the Holy Grail—another war breaks out in Fuyuki City. Shirou Emiya—the adopted son of Kiritsugu Emiya, who was a participant of the previous Holy Grail War—resolves to fight, carrying out Kiritsugu's dying wish. Shirou attempts to protect Sakura, a girl from the Matoi family who has been by his side for over a year. But once the Holy Grail War starts, there's a change in the air of Fuyuki City. Murders abound across the city, and the atmosphere grows ominous. The battle starts to go awry as secret maneuvers by unseen forces are put into play.

Synopsis from Anime News Network