Nenji Kashiwazaki, also known by his old shinobi code name Okina, is a former high-ranking member of the Oniwabanshū, the shinobi network that served the Tokugawa shogunate during the Bakumatsu period. After the Meiji Restoration, he retired from active duty and settled in Kyoto, where he runs the Aoiya, an inn and restaurant that once served as the Oniwabanshū’s headquarters. Despite his advanced age and seemingly carefree demeanor, Okina remains one of the most skilled fighters and sharpest strategists from his organization, having been the only member who could fight the former leader on equal terms. He was offered the leadership role after the previous leader stepped down, but he declined, believing the position should go to a younger person, and instead recommended Shinomori Aoshi to take command. Okina then served as an information agent in Kyoto, and after retiring he raised Makimachi Misao, the granddaughter of the previous leader, as his own ward.

Okina’s outward personality is that of a jovial, sometimes lecherous old man who enjoys drinking games and the company of young women, often giving the impression of a harmless pervert. Beneath this facade, however, he is perceptive, cunning, and deeply loyal. He harbors no personal ambition for power and genuinely wishes for the younger generation to forge their own path. His motivations are rooted in protecting the people and the legacy of the Oniwabanshū, as well as supporting those who strive for peace. In Rurouni Kenshin Part III: The Legend Ends, Okina uses his still-active intelligence network to provide crucial information to Kenshin Himura, helping him locate the swordsmith Arai Seikū and the master Hiko Seijūrō. When Shinomori Aoshi, now consumed by a desire to defeat Kenshin, lies in ambush on a secret route, Okina confronts him to buy time. Despite his age and the severity of the wounds he receives, he fights with his signature steel tonfa, exhibiting the formidable combat skills that once made him a feared shinobi. In the live-action adaptation, he ultimately succumbs to his injuries, sacrificing himself to protect the people he cares about and to give Kenshin a chance to reach his final confrontation.

Okina’s key relationships center on the Oniwabanshū circle. He raised Misao and treats her like a granddaughter, and she looks up to him as a father figure. His bond with Aoshi is complex: he respects Aoshi’s abilities and chose him as successor, but is saddened by Aoshi’s descent into a path of vengeance. With Kenshin, he forms an alliance based on mutual respect and a shared desire to protect Kyoto from the chaos stirred by Makoto Shishio. Okina’s development is subtle: he transitions from a retired, easygoing innkeeper to an active protector who willingly takes up arms again when his family and home are threatened. His notable abilities include masterful use of steel tonfa to block sword strikes, exceptional strategic thinking, and an encyclopedic knowledge of Kyoto’s geography and underworld, all of which he leverages to gather intelligence and guide allies.