"Falling into the Evening" tells the story of a young woman’s confusion when her boyfriend starts a relationship with another. Rica and Kengo have been living together for the past four years. It’s been a very happy time for Rica; the only dark spot being an accident she caused during a shoot for a commercial in which Kengo’s good friend, Shibata, nearly lost his life. The memory of this event weighs heavily on Rica’s conscience. One night Kengo tells Rica that he has fallen in love with a charming but „inscrutable“ woman named Hanako. Kengo moves out of their apartment and, although Rica is terribly hurt and confused, she cannot bring herself to hate Kengo. Nevertheless, she suffers a great deal as a result of their separation. She cannot believe her eyes when Hanako suddenly appears at her door, but this is not nearly as baffling as when Kengo also turns up at Rica’s apartment looking for his new lover. For a while this threesome co-habit in a kind of Ménage à trois, but then Hanako starts staying away for nights on end – without telling either of them where she goes. Kengo soon tires of the situation; Rica, however, decides to find out what’s going on once and for all.