In the Edo period, Iga ninjas Ryuga Akiba and Monji attempt to ambush the Tokugawa clan's treasury convoy led by the Commissioner of Finance to steal its treasures. Meanwhile, under orders from the Tokugawa family, the Koga kunoichi "Aoi" secretly heads to a hidden inn in Edo to steal an important secret letter. Aoi seduces Monji with her alluring charms, but the letter turns out to be a decoy—blank paper. Seizing the opportunity, Ryuga sneaks in and performs an eerie sexual ritual on her, attempting to paralyze her with a numbing drug. However, the drug backfires, causing Aoi to be overwhelmed by a pleasure-inducing coated shuji rod and an enormous cock, ultimately leading her to experience true ecstasy through incestuous sex with her own son. A seductive, sensual tale of female ninja violation and mother-son incest unfolds.