One of the two main protagonists in the series. The dean of the hospital in Sotoba, Toshio resigned from university hospital, returning to take up his father's position when he died. He is fondly given a nickname, "Waka-sensei"(young doctor), by his colleagues as well as the residents. Toshio dislikes both his mother and his late father, as both of them often put reputation of the Ozaki family before anything else. He is childhood friends with Seishin Muroi and Mikiyasu Yasumori. Toshio is 32 years old and married to a woman, Kyoko, whom he rarely sees, and he is a chain smoker. He is baffled by the mysterious deaths and swears to solve the case and protect his village. He is one of the first people to discover the existence of the Shiki and later becomes the leader of the resistance against them.
In the final episode, he has no choice but to escape the village as it burns to the ground.