The story follows two married couples—the and the Misakis —who have been close friends since their college days. After years of marriage, both couples find their domestic lives becoming stagnant and "sexless."

The genius of Modorenai Yoru lies in its psychological realism. The main protagonists don’t just feel lust; they feel seen . After years of being taken for granted by their respective spouses, finding someone who listens, who notices the small things, becomes intoxicating.