My Husband's Affair Partner Was Me! ~My Husband, Who's Been Secretly Writing Letters, Your Pen Pal Is Your Wife~

Sensing the "scent of infidelity" from her husband's trivial actions, the wife begins an investigation into her husband's affair. Then it comes to light that her husband has been exchanging letters with another woman. The wife picks up her pen and, impersonating a 17-year-old merchant's daughter, begins corresponding with her own husband――.