Ozaki is Toshio's father and Takae's husband. Ozaki was born in Ozaki family. He became a doctor and a director of Ozaki clinic and Toshio's predecessor on the work. At some point, he married Takae and fathered Toshio. Toshio followed in his footsteps and became a doctor too. Ozaki died from pancreatic cancer. His death forced Toshio to return to the village and replace him as a director of Ozaki clinic, so the village would have a doctor.
"I'm yelling instead of listening, just like him..."
Ozaki did not seem to have a good relationship with his son and Toshio says that he hated his father. Since he was young, Ozaki pressured Toshio into becoming a doctor, as he was the only Ozaki child.  Toshio also worries that he is becoming like his father.