After Wataru's father-in-law passed away, his wife's mother, Ayano, came to live with Wataru and his wife. They had a cute child and the three generations lived happily together, but... Wataru is drawn to Ayano's engrossing adult sexiness and beauty, which his wife does not have. One day, while Ayano and Wataru are weeding the garden, Ayano gets dizzy and hugs him. With Ayano so close, Wataru's feelings for her explode, and he kisses her without thinking.