Following the death of Saizou, Kabamaru's dreadfully strict grandfather and Iga ninja instructor (sensei), an elderly woman named Ran Ookubo asserts that she received a letter from him requesting her to look after his grandson. Consequently, Kabamaru departs with Lady Ookubo for the large city of Tokyo to indulge in yakisoba, ramen, and chow mein, and to enroll in a standard school—which proves to possess its own peculiar oddities.