Sayuki lost her mother before she could even form memories, and then lost her father during her school years. The family who ran a local dojo took her in and raised her. Growing up under the strict and stern father-in-law, Sayuki gradually began to feel drawn to his awkward yet strong-willed nature. One afternoon, during practice, she accidentally caused her father-in-law to get injured. Overcome with panic and a racing heart, she touched his crotch, forgetting all guilt toward her husband. That single moment became the turning point that drastically changed their relationship.