Cherry blossoms bloom alongside autumn leaves in a mystical realm poised between the human and spirit worlds. As a ritual to safeguard humanity unfolds, high schooler Kakeru Miwa unexpectedly joins a team equipped with advanced power suits to combat the Oni—malevolent spirits that possess humans. The team’s only defense is the Yoroi, a suit blending ancient wisdom with cutting-edge technology. Determined to become a hero, Kakeru takes on the challenge to fight the Oni and protect Ouka Myoujin, the shrine maiden destined to save the world from impending doom.