Yumi and Mai, who are in a sham marriage with a man, are enjoying each other's lesbian lives. One afternoon, as they kiss, their conversation turns to Yuu, the wife of the family next door… Yuu loved a woman named Shiori Eri. She didn't love her because she was a woman; it just so happened that the person she loved was a woman. The two would secretly meet. Unbeknownst to them, Mai had been watching their interactions… Mai quickly realized that Yuu and Eri had an unusual relationship. And when Yumi heard about this…
