Hanagoromo Yumegoromo(2008)

Maho and Mio are twin sisters. They both are 17 years old. One day Maho goes out to look for her sister, but she is raped. After that she gets pregnant, but she has an abortion. As a result of that, she needs to have her uterus removed. The son of an store owner, Hajima Masahito proposes to Maho, but he rejects him because she can't have children. He then decides to marry Mio, her twin sister. Maho wishes them happinness but begins to have an affair with her brother-in-law behind her sister's back.