During the 16th century, a warrior-monk vanquished a powerful demon by pinning it to a rock with an enchanted spear; 500 years later, high school student Ushio Aotsuki, a descendant of the samurai, discovers the demon is still imprisoned in the cellar of the family temple. Although the leonine Tora insists he\'ll devour Ushio, and Ushio threatens to destroy Tora with the Beast Spear, the two become grudging friends, defeating a series of bizarre demons and evil spirits. Their lives are complicated by Ushio\'s friendships with the tomboyish Asako and the more feminine Mayuko.