In the Miso Soup (1997)
In the Miso Soup is a 1997 Japanese-language fiction book written by Ryū Murakami.
It's just before New Year, and Frank, an American tourist, has hired Kenji to take him on a guided tour of Tokyo's nightlife. But, Frank's behaviour is so odd that Kenji begins to entertain a horrible suspicion: his client may in fact have murderous desires. Although Kenji is far from innocent himself, he unwillingly descends with Frank into an inferno of evil, from which only his sixteen-year-old girlfriend, Jun, can possibly save him.