Hayate was once a loyal ninja of the Chigurumatou clan. However the mysterious clan leader Devil Sai desired to conquer Japan through a technique known has "Ninja Henshin Jutsu" (Ninja Transformation Technique) that could change a person into a Kenshin Ninja based on what exists within a person's spirit. Hayate's father, Tani no Maju, fearing the technique would be dangerous in the wrong hands escapes with the scroll. He was later attacked by the clans Yokai Ninja and upon dying, reveals to his son the truth of the Chigurmatou clan's plan. Maju uses the last of his strength to turn Hayate into Henshin Ninja Arashi. Wanting revenge for his father and keep the peace in Japan, Hayate abadons the clan he swore loyalty to and is joined by local Iga ninja: Tatsumaki, his children Kasumi and Tsumuji, and a mysterious ninja who helps Arashi fight against the Chigurumatou clan and their Yokai Ninja. Halfway through the series, the Chigurumatou clan sends the ...