Riho's marriage could have been very happy if it weren't for her mother-in-law. Her husband and father-in-law are both kind, gentle, and love her dearly. On the contrary, her mother-in-law is always unpleasant and tries to pressure her in every way. But Riho is not someone who allows others to do as they please. She seeks revenge by making her father-in-law her own. Seeing her father-in-law masturbating, she uses her seductive body to seduce him, making him listen to her, satisfy her sexually, and constantly speak ill of her mother-in-law to ease her own anger. Finally, when she becomes pregnant, her mother-in-law completely changes her attitude, she respects and takes care of her, not letting her do any work. But she knows that the child she is carrying is not her husband's but her father-in-law's, and she will continue this forbidden relationship...