Six months into marriage, Saki has become the stepmother to her husband's son, Manjiro, a ronin preparing for college entrance exams. With her husband's sex drive nearly nonexistent, Saki constantly struggles with pent-up desire. Meanwhile, Manjiro sees Saki less as a mother figure and more as a woman. She wants to keep this secret hidden. So without thinking, just lean on your stepmom's breasts and indulge.