Chisato Mayama, who has spent her married life being abused by her husband and in-laws, sees her husband, Yuta, walking amicably with a young woman on her birthday. She gets into a struggle with the mistress, and the two are run over by a truck in the heat of the moment. Yuta wakes up in a hospital room and calls his mistress's name: “Runa, I'm glad you're alive....” When she looks in the mirror, she sees that Chisato has been reincarnated as Yuta's mistress.
Chisato vows to take revenge on Yuta with her new life.