One day, Miho, the wife of Amu's husband's older brother, suddenly appears at their home. She had gotten into a fight with her live-in partner and fled, secretly taking refuge here as a lesbian. Amu's marriage has grown stale, with no sex for over a year. Drawn to Miho's unique charm and sensuality, Amu finds herself falling for her. By chance, their relationship crosses the line, and they become consumed by forbidden desire...