In BATTLE ROYAL HIGH SCHOOL, Hyoudo Riki, a regular guy with a penchant for tiger masks and Kung Fu, finds himself in a bizarre predicament. As the mirror image of the sinister Byoudo from a dark realm, Riki becomes entangled in a dimensional clash. Manipulated by the malevolent Fairy Master, Byoudo tries to conquer Riki's world, leading to Riki's partial possession and the transformation of his peers into monstrous beings. Amidst this chaos, an exorcist and the valiant Zankan of the Space-Time Police enter the fray. Now, Riki faces a daunting challenge where survival is the sole objective, with grades determined by a perilous scale of 'Live or Die'.