Tsuma ga Futari?

Jack's wife, Cassandra, is standing in front of him, but he just married another woman that very day! Cassandra was declared dead after she went missing while on a research expedition into the remote Amazon three years ago. Heartbroken, Jack quit his job as a professor and started a new job. Today he married his new boss's daughter. Faced with his first wife, Jack doesn't know what to expect, but he's completely blindsided when she introduces herself as his younger sister and ends up staying in the newlyweds' home. Now there are two wives in the house, and Jack must figure out how to be the right husband! (Source: Renta!)