Yogisha no onna

Saeko is abnormally attached to her older sister, Yumi. When Yumi becomes engaged to Arikawa, Saeko schemes to separate the two. She seduces Arikawa who then becomes confused over his attraction to both sisters. He approaches their father about his dilemma. The father explains that the two are actually half-sisters, Saeko being the result of his affair with Tomoko, a family maid. After Arikawa explains this to the sisters, Saeko's obsession with Yumi seems to end.