As a child, Kiritsugu lived on a small island with his father Nori. Nori's magical work with flowers has captured the attention of a local girl.
Young Kiritsugu (Kerry) enjoys his time with the children as they play in the ocean. Shirley picks him up and she asks him about the origin of the island's name. Kiritsugu states that Arimago is a crab which is right, and Shirley explains that a little girl has no food for her sick mother, so the little girl stole the offerings that were for the sea gods. The gods cursed her and turned into a crab. Kiritsugu finds that story sad, and Shirley informs him that the shrine is near Kerry's home. The villagers don't go over there because it is cursed, yet the villagers think Kerry as Shirley's little brother. She teases him for having a difficult name. Shirley could not pronounce his name. At Kiritsugu's house, he sees his father making the 100th flower. Among the flowers, the father tells him that he has altered the time flow making the flowers unable to wilt. Then, Shirley reveals her flower, and the father explains that Shirley is imitating his magic. He remarks that she is grasping the basics. While they eat lunch, Kiritsugu asks his father if he can practice magic. However, the father tells him that he is not ready and that there are risks. He comments that Shirley has enough experience. Later that night, Kiritsugu observes his father teaching Shirley. On the following day, the priest forbids Shirley from entering that house; Shirley objects to Father Simon's proposal. As the day ends, Shirley reveals that Kiritsugu's father has given her a dagger as a protection charm. Kiritsugu asks Shirley if she is scared of his father. Shirley replies no and finds his father's magic amazing. She thinks it can help people.
Back at the house, Shirley tells Kerry that sensei's magic can benefit people, but her teacher has given up. She points over to her flower that has wilted. Shirley tells him that he is the true pupil and leads him over to a river. Kiritsugu finds the river beautiful as it reflects the moon and the starry skies. Shirley asks Kerry about his goals such as what will Kerry be when he grows up, and Kiritsugu tells her that's a secret. Kiritsugu blushes a bit when Shirley tells him that she will stay by his side forever. On the following day, Kiritsugu's father asks his son if he went into his workshop. When Kiritsugu says no, his father tells him not to leave the house today. As the day is almost over, Kiritsugu decides to search for Shirley. Arriving at her house, Kiritsugu finds the house empty. Inside, he finds a vial opened. Around the back of the house, he finds dead chickens. Then, he sees Shirley eating a live chicken. When he approaches Shirley, she tries to stay away and bangs her head repeatedly. She tosses Kiritsugu's father's dagger to him and begs him to kill her before she loses control. Shirley bites her arm. Then, the scene shifts to Father Simon who tells Kiritsugu to stay here while he informs the villagers. However, Kiritsugu sees the priest getting eaten alive by mysterious figures, and he locks the door. As the intruders bang the door, a sword stabs through the beast and into the door. There are some caped figures with a crucifix who are attacking the villagers who became evil, bloodthirsty monsters. Kiritsugu escapes, and many villagers are getting attacked by the undead. Kiritsugu finds the village burning down with mages burning down the undead. From behind, Kiritsugu confronts Father Simon who is now a bloodthirsty monster.
Suddenly, Natalia bursts from the wall with the monsters in pursuit, and on the rebound, she easily dispatches them with her guns leaving Kiritsugu in shock. Natalia explains to Kiritsugu about vampires, Dead Apostles. There are two separate groups working separately in exterminating the vampires, Holy Church's Executors and Mages Association. The Executors are zealots who slaughter anyone who defies god. The Mages Association's purpose is finding out who unleash Dead Apostles and keeping any information to themselves. Natalia states she is working with the Mage Associations to look for the mage responsible for creating the Undead Apostle. Over at Kiritsugu's home, Kiritsugu's father burns documents and evidence, and Kiritsugu asks him why he research Undead Apostles. He asks his father if he would do the same to him. Kiritsugu's father states that his research for the Root takes a lot of time and that he has to go back to the drawing board. He tells his son that they have to escape the island. Suddenly, Kiritsugu stabs his father with the dagger, and he grabs the gun nearby and shoots his father repeatedly while remembering Shirley. Kiritsugu tries to throw away the gun, but Natalia grabs him. Natalia finds Kiritsugu's reason to kill his father, a noble cause. She asks him if he wants to bring anything with him, and Kiritsugu replies that he has nothing to save.
The folktale behind Arimago's name can be applied to Shirley. She steals Kiritsugu's father's vials. As punishment, she is cursed as a vampire.
|Emiya Kiritsugu ( x ) ( x ) ( x )||
|Shirley ( x ) ( x ) ( x )||
|Norikata Emiya ( x ) ( x ) ( x )||
|Natalia Kaminski ( x ) ( x ) ( x )||
|Takashi Takeuchi||Original Concept||Character artist and cofounder of Type Moon, who's work includes the originals of Tsukihime, Fate/Stay Night, Kara no Kyoukai, and CANAAN.|
|Gen Urobuchi||Original Concept||Gen Urobuchi is a Japanese author and the original creator of the Fate/Stay Night series.|
|Yuki Kajiura||Music||A anime composer who is known for providing music anime created by Bee Train and the .hack series.|
|Kalafina||ED Song: "Manten (満天; The Whole Sky)"|