A few years into their marriage, Hibiki has been striving to be a 'good wife' for her husband. However, the distance between them only grows wider, and she is at a loss as to how to return to their former life. One day, Hibiki meets Aoi, the husband of a friend who lives nearby. As they share their troubles with each other, the two grow closer and end up committing adultery for the first time in their lives. However, Hibiki has no idea that the price she pays for her first-ever affair (Kaikan) is far too high...
