Saeki's baby was the child of Saeki and her ex-husband, the nephew of Saeki's sister and the cousin of Miki. The baby was a boy, but was sadly stillborn. His death was the catalyst that caused his mother's depression and eventual suicide.
Saeki and her husband had apparently been trying to conceive for years, but had difficult doing so. Saeki began using fertility treatments, which eventually worked, leading to her falling pregnant. When Saeki's gynecologist confirmed she was two months pregnant, Saeki rang her husband to give him the good news and he expressed great joy at her pregnancy.
Saeki also told her older sister and niece Miki of her pregnancy. Whilst Miki was pleased for her aunt, Saeki's sister was unimpressed. She accused Saeki of only getting pregnant to keep her husband happy and expressed jealousy towards her sister and her happiness. Saeki hoped that the baby would be a girl and began making lots of stuffed animals for her child. She also promised to make Miki a cuddly animal too, even though Miki was in high school. Saeki stated in her online diary that if the baby was a boy he may not want the toys, though she could always give them to the other children in the neighborhood if that was the case.
Sadly, when she was several months into her pregnancy, Saeki noticed she could no longer feel the baby moving, indicating he had died. When Saeki delivered the baby, she was heartbroken to discover this was indeed the case. Saeki stated that the baby "looked just like his father".
Saeki and her husband held a funeral for their son, choosing to have him cremated. They also moved all the toys Saeki had made for the baby into the basement, but they still found no closure. Saeki became very depressed over her baby's death, feeling that people even blamed her for the stillbirth. Her sister was quite cruel to her, laughing and saying that she didn't deserve to be a mother anyway (though this was likely due to her hysteria). Saeki's husband was also unsupportive and eventually left her, saying he wanted to "raise a happy family" and couldn't cope with her mental problems. This only made things worse for Saeki, who eventually committed suicide.