The Mukai couple finally take their honeymoon four years late, while the Satsuki couple embark on their first trip together in five years. Both have long anticipated staying at the same famous inn, but a travel-agency mistake leaves their rooms double-booked. The replacement hotel offers no meals or bath, an unacceptable downgrade after so much planning. As tempers rise between the couples, the wives suggest that everyone peacefully share the inn's single available room, setting the stage for an unexpected partner swap.