Strike the Blood is set on Itogami Island, and it's known as the Demon District because it's the home of various magical beings who have been authorized by the government to live there for protection and research purposes. The main character of the series is Kojou Akatsuki; three months prior to the start of the series, he became the Fourth Progenitor, which has given him vampiric powers. A girl named Yukina Himeragi has been given a mission by the Lion King Organization to observe Kojou, and if she deems him to be dangerous, she has been ordered to kill him.
Episode 15 picks up with the battle on the roof between the Meyer Sisters, Yuuma, Kojou, and Yukina. Kojou is surprised when he sees that Dimitrie is also there. Kojou learns that Yuuma is planning to use the power in his body to open the prison barrier and free her mother. The Meyer Sisters launch an attack with their forest monster, and Kojou and Yukina are trapped in its branches. Just as all hope seems lost, Sayaka and La Folia suddenly appear and free them. They were brought there through Kensei Kanase's magic; La Folia had requested his temporary release because they needed to be able to use his power.
Yuuma then uses magic to go where she needs to go. Kensei uses his power to open a gate near the prison barrier, and Kojou and Yukina are sent to deal with Yuuma. Sayaka and La Folia stay on the rooftop to fight the Meyer Sisters. Once Sayaka and La Folia figure out what the monster is and how to effectively fight the Meyer Sisters, they are able to defeat them.
The majority of the episode focuses on Yuuma, Kojou, and Yukina. It's revealed that Natsuki, who disappeared back in episode 13, is near the barrier. It turns out that she is the jailer, the door, and the key to the barrier. Kojou tries to reason with Yuuma, but to no avail. Her Blue Knight tries to kill Natsuki, but Kojou is able to save her. In order to resolve the storyline, Yukina is forced to use the technique with her Schneesturm Wolfin that she didn't want to use.
After the ending credits, just when it seems everything is going to be returning to normal, something very unexpected happens that could have a drastic effect on the series going forward.
Well, I ended up being right in last week's writeup when I said that this episode would end up wrapping up this particular story arc. However, there's something that's bothering me: where is Nagisa? It was mentioned that she was gone in episode 14, but we didn't see her at all in this episode. Where did she go?
And I was glad to see Sayaka play a major role in this episode. As I said in the writeup for episode 14, she had pretty much been on the sidelines recently in the main action of the story. I also thought that Sayaka and La Folia worked really well together in order to defeat the Meyer Sisters.
Now that this story arc is over, I'm looking forward to seeing what the next story arc is for Strike the Blood is and how it will be progress the overall story of the series.