Saeki's husband is a minor character in Paranoiac. He never actually appears in the game and is only mentioned. He is the former husband of Saeki, the uncle of Miki Takamura and the father of Saeki's unborn child.
Not much is known about Saeki's husband, save for the fact he was a wealthy man. It is possible that the house where the game takes place originally belonged to him, given that it is very spacious and would probably cost a lot of money. At some point in his life, he met Saeki, fell in love with her and married her.
The couple was apparently very happy together, especially when Saeki became pregnant with his child. Sadly, Saeki lost the baby and fell into deep depression. Saeki said that the baby, a boy, looked just like her husband. Saeki's husband felt he could not cope with his wife's deteriorating mental state as well as losing his child, and the couple drifted apart. Eventually, Saeki's husband divorced her and left, never to return, devastating his ex-wife and likely contributing to her eventual suicide. Saeki's husband stated he wanted to "raise a happy family", so it is possible he remarried. It is unknown if Saeki's ex husband ever contacted his former wife again before her death, or if he was even aware she had passed away.