育有一子的仁科志保（佐津川爱美饰）与其丈夫仁科浩介（千贺健永饰）对夫妻二人之间的夜生活提不起兴趣而感到烦恼。某日，丈夫浩介突然向志保提议一起去参加“夫妻交换派对”。一开始志保并不同意，但在丈夫坚持下最终被说服。起初志保抱着“只是去看看”的心态，不太情愿地参加了名为“深夜水族馆”的夫妻交换活动，没想到在此过程中她逐渐发现了交换夫妻的美妙之处……
Nishina Shiho, is a young mother and raises her child while working as a writer at home. Although she enjoys her life and has a perfect husband, she is troubled by her lack of sex with her husband, Kosuke, who has ED. Due to this, Kosuke suggests that they attend a “couple exchange party”, where couples change their partners for various reasons.