湯布院殺人事件 (Yufuin satsujinjiken, The Yufuin Murder Case, 1994) is a not very interesting mystery by UCHIDA Yasuo (内田康夫). The main characters are IZUMI Naoto (和泉直人), a professor who has just resigned from the law department of his university in protest at its involvement in a corruption scandal, and his wife Asako (麻子). His former students honour his departure with the gift of a "honeymoon travel pass" which he can use with his wife on trains throughout Japan. Uchida's books are often the basis for television dramas that combine a murder mystery with views of an interesting tourist destination somewhere in Japan. In this case the television drama was already invisaged before the book was written. Indeed the travel pass element of the plot is there because Japanese Railways were sponsoring the television show. (At the time the book came out, the TV drama had been dropped; but it was finally televised in 2002.)
The mystery starts with the murder or perhaps suicide of the secretary of the politician involved in the corruption scandal, then shifts to a traditional drama surrounding machinations within a wealthy rural family whose patriarch is lying on his death bed. As the death toll rises we wonder how the two stories fit together. The answer (SPOILERS, I suppose) is that they don't; and the original mystery is basically dropped in place of another one.
My memory of the few Uchida books that I've read is that they do occasionally have an interesting idea somewhere in them, although swamped by the lukewarm soup of platitudes that serves as fodder for mid evening television drama. In this case, anything promising in the story leads only to disappointment. On their way to their holiday in Kyūshū, the Izumis are suddenly summoned by the train conductor to come and look after their child. When they find the conductor, he is with an unknown boy, six years old, who has a letter asking them to accompany him to Yufuin (an peaceful onsen town in Ōita). Who is the boy and why has his mother taken such a strange method to send him to this distant town? The answers prove to be both implausible and uninteresting.
The mysteries of the actual murders are poorly supplied with clues; but there is no chance that you will not spot the killer.