Labyrinth of the Blue Witch (蒼き魔女の迷宮 Aoki majo no meikyū) is the fourth novel of the Strike the Blood series.
Itogami Island is abuzz with preparations for the Halloween festival, and who should be visiting for the occasion but Kojou Akatsuki's friend from elementary school, a girl named Yuuma Tokoyogi. But as Kojou reunites with his friend, his homeroom teacher, Natsuki Minamiya, goes missing! Meanwhile, a strange space-time distortion is turning the sanctuary of Itogami Island into a labyrinth from which escape is impossible. And what's behind the physical changes that come over Kojou whenever he has physical contact with Yuuma?
- Chapter One: The Calm Before the Storm
- Chapter Two: My Dead Childhood Friend
- Chapter Three: Fancy Dress Parade
- Chapter Four: Hidden Prison
The volume was adapted into episodes 13-15 of the anime.