TV-Series
Description
Kotarou Fuuma is the leader of the Fuuma Village in the hidden ninja world of Nabari. He is a tall man with long black hair tied back in a low ponytail, often seen wearing semi-rimless rectangular glasses and traditional Japanese clothing. His true age is kept secret, but it is revealed that he was born in the Edo period, making him over one hundred years old. He was unable to accept the prospect of dying without having touched the wisdom of the Shinra Banshou, and he used forbidden arts to cheat death and extend his life.

His outward personality is that of an eccentric and hedonistic individual. He frequently proclaims a love for women and claims that if he possessed the Shinra Banshou, he would use its power to create a paradise where all the women in the world would love him. His allies, however, note that he is lying most of the time. This facade hides a deeply ambitious, cunning, and ruthless nature. He is a master manipulator with a strategic mind who has planted spies in other ninja villages to keep himself informed. His true motivation is an obsessive lust for knowledge and power; he wishes to acquire the Shinra Banshou to become a god-like being of absolute wisdom and transcend human understanding.

In the story, Kotarou Fuuma is initially presented as a neutral party and a potential ally. He is the foremost scholar of ninjutsu and has authored nearly every text regarding the Shinra Banshou, so the ninja of Banten Village seek his help in finding a way to remove the scroll from its young vessel, Miharu Rokujou. As the narrative progresses, he is exposed as a long-term antagonist who has been secretly collaborating with the Grey Wolves. It is revealed that he killed Miharu ten years prior to the main events, forcing Miharu's mother Asahi to activate the Shinra Banshou to revive her son, which set the current conflict in motion.

He is the leader of the Shimizu clan, overseeing Raimei and Raiko Shimizu, though they eventually turn on him when his true loyalties are laid bare. He shares a complicated history with the immortals Koichi Aizawa and Shijima Kurookano, who sever their alliance with him. His main adversary is Tobari Kumohira. He views Miharu solely as a vessel for his goal and feels an almost reverent fascination for the female spirit of the Shinra Banshou, whom he calls Shinra.

Over the course of the series, he develops from an eccentric scholar into a fully revealed scheming villain. His ambition peaks when he nearly succeeds in extracting the Shinra Banshou from Miharu. In the final confrontation, he is killed by Tobari. Unable to sustain the forbidden jutsu that kept him alive unnaturally, his body rapidly decays and rots away to nothing, marking the end of his centuries-long pursuit of godhood.

His notable abilities stem from his immense knowledge of ninjutsu. He is proficient in techniques such as Hengejutsu, a transformation skill, and Nawajutsu, a rope technique. His most significant abilities are the forbidden arts Tenpenka and Kira, which allowed him to cheat death, change his appearance to a younger form, and operate under the alias Inasa as the leader of a secret intelligence unit. Beyond direct combat, his most formidable asset is his vast intelligence network, which lets him stay several steps ahead of his opponents.