Worried about his mother-in-law, Ayaka, who was forced to live alone after her husband's death, Kazuya visited her parents' home with his wife. What he glimpsed there was a fleeting, troubled expression hidden behind Ayaka's smile. Despite knowing it was wrong, he couldn't help but feel attracted to Ayaka, who seemed to be shrouded in such shadows. How could he be thinking such things when he had a wife? Kazuya blamed himself, but he couldn't stop being drawn to Ayaka...
