Ayana married a divorced man much older than her. The man had a son, Tatsuya, from his previous marriage, but because Ayana and Tatsuya were close in age, the two quickly became close like siblings and lived together in harmony. However, after Ayana became pregnant with her father's child and gave birth safely a few months ago, Tatsuya began to act strangely, feeling alienated and left out of the group...