Sakiko is a 40-year-old editor working at a publishing company. While she is competent at her job, she can be a little lazy and absent-minded in her personal life. The story unfolds when Sakiko and her husband get involved in an accident with another couple. This incident causes the happy lives of both couples, which they had taken for granted, to suddenly crumble. Moreover, the "third Friday secret" involving her husband comes to light.