Sugitani Zenjubo is a Kouga ninja and master sniper wielding the Tanegashima rifle. Initially driven by wealth, fame, and a desire to prolong the Sengoku era's chaos, his first major action is an assassination attempt on Oda Nobuna during her retreat at Mount Hiei. He fires twice but fails to kill her; one account notes an unexpected hesitation where he deliberately shifts aim from Nobuna's face to her abdomen, leading him to believe she possesses divine protection.

This failure triggers a severe psychological decline marked by heavy drinking and self-deprecation. He later accepts a mission from the Oda clan to assassinate Takeda Shingen, which ends as another failure due to external interference. These repeated defeats erode his resolve, culminating in an existential crisis. During a final failed operation, he experiences enlightenment upon grasping Sagara Yoshiharu's insight that assassins cannot alter history. This realization, combined with Shingen's decision to spare him, solidifies his transformation.

Sugitani ultimately abandons his life as a ninja and sniper, retiring to become a monk. This transition signifies a complete departure from his former ambitions and acceptance of a passive role within the era's conflicts.