Kai, a tough-looking but kind-hearted young man, saves a girl from delinquents but gets caught in a car accident. When he wakes up, he finds himself in the mysterious “Shadow World,” a realm between life and death where people’s shadows take on powerful forms as Shadow Beasts. Learning he isn’t actually dead, Kai embarks on a journey with his shadow, a young girl, to find a way home. However, he soon becomes caught in the world’s power struggles, facing unexpected dangers along the way.