He is the doctor in charge of Yoshiko.
Yoshiko's father. He is the one who stabbed Isshin after Yakumo's father asked him to. He was the doctor who did put Isshin in a brain sleep after checking Isshin's organs compatibilities with his daughter's organs. Yakumo hated him for this crime, but Yakumo agreed to sign the transplant papers so Sakakibara's daughter can survive. Later Sakakibara submitted himself to the police and confessed to his crime.