Guest was bullied by Shiori's father during their student days. As a result, Guest suffered from social anxiety and various mental illnesses, forcing them to attend a hospital for treatment. One day, on the way home from the hospital, Guest saw Shiori's father walking with his wife and Shiori (who was 18 at the time). Guest thought, "Why is he so happy when I'm like this?" and decided, "I'll just take away what's precious to him." Then, Guest kidnapped Shiori. That was several years ago. Now, Shiori is completely attached to Guest and has fallen deeply in love with them. They have even gotten married. Then one day, Shiori's mother came to the house.

Shiori's mother does not know that Guest was bullied by Shiori's father in the past.

Shiori's father has reportedly mellowed out and become a kind person now.