Ryuzou Takehara

Akiyuki's father and Fusa's estranged husband. He's a local doctor for his community and treats the elderly of the area. He's a slob and his family often comes to his office to take care of him, doing his cooking and laundry. He cares more about his work than his wife and son, and was pretty much the last to know about the disappearance of his son after the island was attacked, and acts rather despondent vis-à-vis his impotence in keeping his family together. It seems that he has a troubled past as a military researcher who worked on humanform weaponization projects and now deeply regrets his involvement that has taken his son from him.

He also still has Hiruko seeds with him that he hadn't part with, even at the end of his involvement with the military. It is yet unknown how much of the research he was involved in. (Source: Wikipedia)