Not just Kirei Kotomine—every time one of the movie's other major characters appeared, it was interspersed with a flashback to their past.
Shinji did it to save time. There was no way they could take their time laying the groundwork like the Fate/Zero anime had. But if they only showed brief snippets, they could save a lot of time.
There was a downside, too: all the jumping back and forth in time could confuse viewers who didn't like having to think too hard.
So, to make the movie easier to follow and help viewers tell when each scene was taking place, Shinji had deliberately used color to distinguish the flashbacks from the present.
Scenes set during the Holy Grail War were darker in tone, emphasizing the war's seriousness and brutality;
The characters' memories were brighter and more colorful;
As for the Heroic Spirits' memories of their lives, the edges of the image were blurred, creating a hazy, dreamlike effect.
That way, unless they were color-blind, viewers could easily tell when the scene currently playing on screen was set.
That still wasn't enough for Shinji. To highlight how important time was in this movie, he'd studied the Fate/Zero novel and anime. Every time the scene changed, a countdown appeared in the corner of the screen.
Time limits were practically a staple of commercial blockbusters. A countdown was a simple and effective way to create tension.
But Shinji had taken it too far. He'd put the whole movie on a countdown, pushing the time-limit gimmick to the extreme.
The audience knew that when the countdown hit zero, the war would end and the Holy Grail would appear. So every time they saw it, they couldn't help feeling a little tense.
"Matou's kid is so mean. This countdown is practically baiting me," Aoko