This Transient Life (1970)

Set around a remote Buddhist monastery, it features Masao, a young son of a rich merchant who doesn't want to follow his father into business or go to college, preferring to study under a famous Master how to make Kannon statues of the Goddess of Mercy. At the same time, his sister Yuri is struggling to find a potential husband, only for it to explode when their horseplay in masks one day leads to an incestuous consummation that brings disaster to all. They fall in love, she gets pregnant but it's assumed to be someone else's, who she marries. A monk at the monastery knows the truth, and confronts Masao, who goes off instead to the master sculptor to be his assistant, only to then begin another affair with his wife, who in turn seduces her young son who, in horror, blames the whole business on Masao and sets out to kill him.