When my son Katsuhiko was seven years old, we got divorced, and he had to leave his home because I lost custody of him. Several years later, after my husband passed away, I returned to our house to take care of Katsuhiko, who was still a student at that time... but he became a shut-in and started skipping school. I couldn't figure out why he stopped going to school, so I struggled every day to bridge the gap between us. During those difficult times, Mr. Matsuda would visit our home, offering me support and encouragement. Little did I know then that he was secretly plotting something against me...