When Akihito sees a girl about to jump off the school roof, he surprises even himself as he races up the stairs to rescue her. Much to his surprise, the girl he saved is a Spirit World Warrior. And as a half-youmu, he’s now her prey!

Now that Akihito and Mirai have been reunited, they must work together to defeat Beyond the Boundary’s core. But what will happen to Mirai and Akihito once it has been defeated...? Will either of them survive?

This episode takes place two years prior to the anime series and begins when Hiroomi receives a request for a job from his older sister Izumi: to subdue the invulnerable half-yōmu Akihito. Hiroomi's younger sister, Mitsuki, encounters a dark silhouette in the street on her way to follow Akihito and her brother.