"Strike The Blood III" continues the story of Kojou Akatsuki, a high school student who becomes the Fourth Primogenitor, a powerful vampire known as the "World's Mightiest Vampire." The series is set on Itogami Island, a man-made island where humans and supernatural beings coexist. Kojou's life takes a dramatic turn as he navigates his newfound powers and responsibilities while protecting those around him.

The narrative in "Strike The Blood III" revolves around Kojou and his companions, including Yukina Himeragi, a Sword Shaman tasked with monitoring him, and other allies such as Asagi Aiba, a tech-savvy friend, and Natsuki Minamiya, a powerful mage and teacher. The series introduces new challenges as Kojou faces off against powerful enemies, including other Primogenitors and supernatural entities threatening the balance of Itogami Island.

The plot delves into the complexities of Kojou's relationships, particularly with Yukina, as they confront external threats and internal conflicts. The series explores themes of loyalty, sacrifice, and the struggle to maintain peace in a world where supernatural forces constantly clash. Kojou's growth as a character is central, as he learns to harness his abilities and protect his friends and the island from destruction.

"Strike The Blood III" maintains a balance between action-packed sequences and character-driven moments, with a focus on the dynamics between Kojou and his allies. The series introduces new characters and expands on the lore of the "Strike The Blood" universe, providing deeper insights into the world of Primogenitors and the challenges they face. The narrative builds on previous events while introducing fresh conflicts, ensuring continuity and progression within the overarching storyline.