The book was a good read and the author aptly explained the desperate situation. But when repeatedly stating that he knew what having his own child was like, I don't agree. He never said that he would give his life up to save her own and he never begged God to take on Chika's suffering in place of her. Biological parents would have done both.
It seemed that he was trying to use his own power to save Chika. Most actual parents most likely would have chosen not to prolong her suffering.