Yuji, the son of a concubine, lost his parents and was taken in by his legal wife, Kaho. Kaho was not blessed with children, and as a result was treated coldly by her father-in-law. Kaho's worried sister, Ayaka, proposes a plan to use Yuji's sperm to make it appear that Kaho is pregnant with her husband's child. At first, Kaho refuses, but her feminine instincts begin to stir at the young, powerful penis...