悉心照顾老公和儿子的全职妈妈星野友美（永作博美饰）、在电影公司供职的职场女强人早川薰（石田百合子饰）以及家境平庸心宽体胖的三上春子（佐藤仁美饰），是现年41岁的老同学。学生时代她们形影不离，彼此心中留下了快乐、悲伤的回忆。借着同学会的机缘，好朋友们再次见面，友美却从闲谈间察觉丈夫洋介（藤木直人饰）似乎和薰抱持着不正常的关系。在一次争执引发的意外后，两人惊讶地发现她们居然互换了身体。万般无奈之下，她们只能各自进入对方的生活，品味着从未有过的生活方式和苦辣酸甜。与此同时，春子的丈夫则和名叫远山冬子（谷村美月饰）的女性继续保持联系，看似大大咧咧的春子，也隐隐察觉到丈夫的秘密。三个女性，共同经历着人生的变动

In the autumn of their first year in high school, some incident spurred Tomomi and Kaoru to promise to be friends forever. However, at their present age of 41, the two of them have gone through different lives. Tomomi has built a happy family that everyone envies while Kaoru lives for her career as a movie producer. The differences in their lifestyles have created a distance between them. The two friends meet again for the first time at a class reunion after 20-something years and return to their former closeness. However, Tomomi has one suspicion. Kaoru knows too much about her own family. Is her husband and good friend having an affair? When Tomomi gets to the bottom of the matter, an inconceivable fate awaits her and Kaoru. The two of them are at the mercy of a harsh destiny, and before long, they learn what is hidden in each other's hearts.