Yui is a young woman who, as a favour to her sister, goes to a stranger's family to decline a marriage request addressed to her. The latter, too busy, doesn't have time to go there herself... But for Yui, what seemed like a burden turns out to be a real godsend: when she meets Kosuke, the suitor, it's love at first sight... Yui then takes her sister's place and a new love story begins!