Tsuma ga Futari?

A man named Jack had married a woman named Cassandra, who was later declared dead after vanishing during a research trip in the Amazon three years prior. Afterward, Jack left his professor job and took a new position, eventually marrying the daughter of his new employer. On the day of his second wedding, he is surprised when Cassandra appears before him. She claims to be his younger sister and moves into the home he now shares with his new wife. Jack is left to navigate the situation with two women in his life who both believe they are his wife.