Whoa, another episode telling the story of Kiritsugu's past. It was just very dark and got really saddening near the end. I actually don't like this episode much and it's also surprising how dark Kiritsugu can get. Besides his past, there's no other characters involved except the victims getting targeted by our protagonist along with his teacher. Pretty much in other words, this episode is just a filler with action. But, the action part is still what I like. Now when will get back to the present? Probably on the next episode. So overall, a filler of our protagonist's past.
Conclusion: A second filler of Kiritsugu's past.