Hanayome Made no Kyori

The year is 1938. Dee is studying to become a nurse. Her breath catches when she meets her beautiful sister's boyfriend, Mark, for the first time. She has never met a handsome, cheerful man with such a booming voice before. Even while dating her sister, Mark treats Dee as a lady, and she falls for him and the way he takes her seriously. Dee hopes that he will hurry up and marry her sister so she can forget about her feelings for him. But Dee has no idea what her sister is feeling. She also doesn't know about Mark's uninhibited relationships or his rash and reckless dream. (Source: Renta!)