Sei Shima, an eighteen-year-old boy with fox ears, finds himself in a predicament when he, his younger sister, and his girlfriend of eight years are dragged to their mother's homeland of Japan to further (or rather, begin) his training as a summoner.
The true predicament arises, however, when Sei comes face-to-face with his teacher, Kino Ayanami.
Suspicions and tensions rise within the household not only concerning Sei's loyalty toward his current love, but also for the true reason the trio is undergoing such vigorous training.