Gennosuke is the primary character in the Japanese anime The Kouga Ninja Scrolls. As the grandson of Lord Kouga Danjo, Gennosuke was chosen to be one of ten warriors to represent their clan of Koga Manjidani against the chosen ten of the rival Iga Tsubagakure clan. Upon his grandfather's death, Gennosuke ascends to take leadership of the clan.
In many ways, Gennosuke is as much an oddity among his clan as Oboro is among hers. An idealist and scholar who believes in looking to the future instead of being dominated by the past, Gennosuke views the pursuit of any grudge to be an ultimately pointless and self-destructive practice. His sense of principles remain even after learning of the renewed conflict between Kouga and Iga, prompting him to lead the Koiga on an expedition to Sunpu to plead with former Shogun Ieyasu and Hattori Hanzo the 4th to reinstigate the treaty before any more senseless bloodshed occurs.
Yet despite being a man of peace, if pushed into a corner Gennosuke is more than capable of killing anyone who threatens him or his clansmen. In addition to his skill with the sword, Gennosuke wields a power called Dojutsu which he learned from his teacher and uncle Muroga Hyouma. A hypnosis technique, Dojutsu reverses the homicidal intent of anyone who meets the stare of its user directly. In other words; if someone expresses hostility toward him, Gennosuke is able to will his enemies into killing themselves instead of him. Even Yakushiji Tenzen thinks twice before challenging Gennosuke directly.
Before the cancellation of the treaty, Gennosuke sought to build a lasting peace between Kouga and Iga by marrying Oboro, the Iga Princess whom he loved to a great extent. His feelings for her remain even as the body count among both clans rises, filling him with torment as he struggles to reconcile his personal feelings with the duty demanded of him as his clan's leader. In the anime, Gennosuke carries with him a flute that he often plays for Oboro and which represents their hope of bringing peace to the clans. After learning of the Hattori Truce's absolvement, he leaves the flute behind in Tsubagakure as a farewell present for her.