Miss Oyu

Shinnosuke is introduced to Shizu as a prospective wife, but he falls in love with her widowed sister Oyu. Convention forbids Oyu to marry because she has to raise her son as the head of her husband's family. Oyu convinces Shinnosuke and Shizu to marry so that she can remain close to Shinnosuke.
(Source:
IMDb)
~~ based on the 1932 novel "The Reed Cutter" (芦刈) by Jun'ichirō Tanizaki (谷崎潤一郎).