Fate/stay night prequel season 1

In order to obtain the "Holy Grail", a miraculous technique that can grant all wishes, seven magicians summoned seven heroic spirits to launch a holy war. They must fight to the end, because in the end only one person can obtain the power of the "Holy Grail" - and the "Holy Grail War" begins. This holy war has not subsided because of the past three battles; now, the fourth battle is about to begin. Determined to win, the magicians gathered at the battlefield called "Fuyuki" to face this sacred battle. However, one of them did not understand why he was fighting. He is──Kotomine Kirei. Kotomine Kirei couldn't understand why he was chosen and given the Command Seal. However, fate will lead him to meet another participant in the war, that is──Emiya Kiritsugu. Emiya Kiritsugu desires the "Holy Grail" more than anyone else. He used all cruel means to achieve his goal. In the super popular game "Fate Stay Night", the fourth battle 10 years ago is only briefly mentioned. The truth about Shirou's adoptive father, Rin's father, and the young and energetic Kirei Kotomine going to war will now be revealed one by one...