When a young Arimasa Tsuchimikado saves and transforms an injured cat named Kagetsu into a human, little does he know that Kagetsu belongs to the shape-shifting Kouga tribe. As years pass, Arimasa, ostracized for his mixed heritage, becomes the village's reluctant guardian against otherworldly threats. Meanwhile, Kagetsu faces a pivotal choice of gender identity, a transformation possible only through intimacy. Amidst clan opposition and a looming supernatural assault on the village, Arimasa is pushed to make crucial, unwelcome choices to safeguard his fragile existence.