well, sure Mikami could be quite harsh... but there's Okinu-chan, who is the single sweetest girl in all manga IMO, the perfect Yamato Nadesico out there. Besides, Mikami IS super rich, intelligent, having enough firepower in her personal arsenal that can start WW3 and bring the entire human race to extinction while she can live on safely and comfortably in her private bunker. When you consider this, at least it's better to become her pet instead of her enemy
Not to mention there's also Lucciola, Shoryuki, the wolf, the fox... and various other hot (or cold
) female demons, gods and spirits out there... (Yokoshima Tadao indeed has some special attraction towards supernatural things I guess
)