Frolic of the Beasts by Yukio Mishima
Trade paperback format. Translated from the Japanese by Andrew Clare.
Set in rural Japan shortly after World War II, The Frolic of the Beasts tells the story of a strange and utterly absorbing love triangle between a former university student, Kōji; his would-be mentor, the eminent literary critic Ippei Kusakado; and Ippei's beautiful, enigmatic wife, Yūko. When brought face-to-face with one of Ippei's many marital indiscretions, Kōji finds his growing desire for Yūko compels him to action in a way that changes all three of their lives profoundly.