Mari Asai—the main female character of the story, Eri’s sister and Takahashi’s friend. Eri Asai—Mari’s sister, a beautiful model who has been sleeping for a couple months. Tetsuya Takahashi—the main male character of the story, Mari’s friend, and a trombone player. Kaoru—the manager at Alphaville, a big woman who was once a wrestler. Komugi—a worker at Alphaville. Korogi—a worker at Alphaville, a runaway who is afraid to use her real name. Guo Dongh—a Chinese prostitute, nineteen years old, and an illegal alien controlled by a gangster. Shirakawa—a married man who works all night and beats up the Chinese prostitute.
After Dark is less like a novel and more like a collection of very short, short stories or vignettes. Readers know little about most of the characters and only enough to guess at the rest. Eri is beautiful and troubled. She is praised, pampered, and preferred by her parents over Mari, or at least that is how Mari sees it. Mari, on the other hand, must muster enough confidence to make it on her own. She loses herself in books and studies. She has learned to be aloof, such as when Takahashi takes an interest in her. She is the type of person who is more than she realizes. She puts on no airs because she doesn’t believe she has the right to.
Takahashi is similar to Mari in many ways except that, whereas Mari is quiet, Takahashi cannot seem to stop talking. Mari keeps her thoughts to herself for the most part, but Takahashi appears to have to vocalize his thoughts to better understand them. Takahashi often talks around his topics when they become too personal. For example, he keeps referencing Eri’s beauty and attractiveness to keep Mari’s interest. Strangely enough, this doesn’t seem to bother Mari, as she exhibits no signs of jealousy. Finally Takahashi admits that his real interest is in Mari, which comes as a surprise to Mari. She is a bit self-deprecating and asks Takahashi why he would want to see more of her.
Neither Takahashi nor Mari has much support from their parents and neither is very anxious to go home. The chances of their becoming friends are ill-fated, as Mari is about to leave for China. Gaining this knowledge at the end of the story (as well as the end of the night) intensifies their chance meeting and the few hours that they have spent together. But in the end, they are lone characters who appear to be destined to live apart.
As a matter of fact, most of the characters seem like loners. Eri is alone in her bed. Kaoru and her hotel assistants work behind the scenes, with customers coming into the hotel and registering through a machine. The employees are seldom seen; Korogi even mentions how working in places like this hotel helps her to remain undetected. Guo Dongh, the Chinese prostitute, most likely does not have a friend and is further isolated because she does not speak the local language. And Shirakawa, although he has a wife and children, works during the night while his family sleeps then goes home and makes sure he is asleep before they awaken. So their paths never cross.