Orphaned ninjas Etemaru, Kasumi, and Taizo are raised and trained by the modern ninja organization Shingensai. However, their battle against the evil Goryai clan, who seek to conquer Japan, intensifies when Etemaru falls into an enemy trap and is captured. Enduring brutal torture, Etemaru holds strong as his comrades storm the Goryai stronghold to rescue him—only to walk straight into disaster. The enemy cunningly captures Kasumi and subjects her to a cursed technique called "Inmu," forcing her to experience overwhelming, uncontrollable sexual pleasure. Helpless against the relentless waves of desire, Kasumi is completely overwhelmed. Yet the enemy shows no mercy, driving her body further and further into ecstasy with unceasing stimulation...!