I've been dating Mari, who isn't beautiful but has a good personality, for three years, and we've started thinking about getting married... But one day, I go on a hot spring trip with her parents and meet her mother, Naho, for the first time. I love older women, so I fall in love at first sight with her. However, Naho is also her mother and is married, and I end up heartbroken soon after meeting her. Feeling nervous, I head to the hot spring alone, where Naho is already taking a bath, and even though I know it's wrong, I can't help but touch her beautiful, wet body...