Helen, a blonde, dynamite-bodied power woman from America, learns that a sacred treasure has been stolen and travels to Japan to retrieve it. The thieves are a traditional Japanese ninja clan known as the Kiba Clan. As she pursues them, assassins repeatedly attack, but to Helen, Japan's handcrafted swords are weaker than children's toys. Raised in America with a cheerful and naive personality, she never suspects danger—until she drinks a cup of Japanese-style tea laced with poison. The toxin drains her strength, leaving her completely defenseless and at the mercy of the Kiba Clan's unique torture methods.