Gen Shishio (志々尾 限, Shishio Gen?) first appeared in volume 6 of the manga and in episode 21 of the anime. Shishio aids Tokine and Yoshimori in hunting ayakashi and protecting Karasumori. He is an "integrated half ayakashi" (ayakashi majiri), meaning he can transform part or all of his body into that of an Ayakashi. He was frequently bullied by other children and even his older brothers when he was young. When his power first fully awakened when he was ten, he almost killed his older sister and severely injured his older brothers. Afterwards he was taken in by Masamori and the Yagyou, where he was taught by Atora. Gen learned how to control his full ayakashi mode during a fight with a high level ayakashi from Kokuboro, but before he could finish his opponent, Kaguro — another high-level ayakashi from Kokuboro — killed Gen. Gen's death deeply affected his allies and Yoshimori.

Saito Hiraga, the main male character and primary protagonist of the story, is from modern-day Earth (specifically Tokyo, Japan). While walking down the street a portal opened in front of him, and when he touched it he was sucked through, landing in the Tristain Academy of Magic.These runes glow when his Gandalfr powers activate. As a Gandalfr, a familiar who exists to protect a Void Wizard, Saito has the ability to use any object that was made with the intent of being used as a weapon at an extremely high level of skill. He also becomes significantly stronger, faster and tougher.His partner, the talking sword Derflinger, was also the partner of the Gandalfr six thousand years previously.