Shinobi no Ittoki follows Ittoki Sakuraba, an ordinary-looking boy whose careful, sheltered life is only starting to make sense. His mother, his uncle, and especially his childhood friend Kousetsu treat every step he takes as if it could put him in danger, and Kousetsu shadows him so closely that he can barely think of her as anything but an overprotective friend. That illusion collapses when Satomi Tsubaki, a seemingly sweet second-year student at his high school, asks him out on a date and leads him into a trap. At Tsubaki’s house, Ittoki learns that she intends to assassinate him, and his uncle and Kousetsu arrive just in time to save him, stepping out of the shadows in dark ninja attire and revealing a hidden world he never knew existed.
Forced to accept the truth, Ittoki is told by his mother that he is the 19th heir to the Iga, a noble clan of ninjas now targeted by the rival Koga clan. With his old life shattered, he has no choice but to train at Kokuten Ninja Academy, the only ninja school still operating in Japan. As the conflict between the Iga and Koga closes in, Ittoki must learn how to survive long enough to protect his legacy and decide what kind of future he wants to claim.
