Oguni Gensai is a skilled elderly physician who owns and runs a modest clinic in downtown Tokyo near the Kamiya dojo. A longtime friend of the Kamiya family, the good doctor is frequently called in when a member or ally of the Kenshin-gumi is in need of medical aid. In the anime series, Gensai is most often seen in the company of his two young granddaughters, Ayame and Suzume.
Gensai is a short elderly man with kind, dark eyes and light grey hair that matches his thick Fu Manchu moustache and short, pointed beard. He is always seen wearing a burgundy kimono under his sky blue doctor's jacket and matching hat.
Amicable and grandfatherly, Gensai is always accommodating in times of need and readily available to help celebrate in times of peace and revelry. He cares deeply about his patients and the people in his community and can his sharp observational skills allow him to sometimes serve as a useful source of information regarding the goings-on surrounding the Kenshin-gumi's adventures. His good-nature does appear to have a limit, as shown in his general sense of annoyance towards Sanosuke and his exasperation with Megumi's rare lapses. In addition, the elderly doctor seems to have a lascivious side, as evidenced by his initially lusty behavior toward his lovely new assistant. In the anime, Gensai's constant attachment to Ayame and Suzume seems to foster a slightly more benign temperament.