Hitomi Kobayashi plays Kazumi, a woman happily married to Akio with their daughter Megumi, living a peaceful family life. However, she harbors a past she cannot forget—her relationship with her sister-in-law Hitomi Shimizu, who became her sister when Kazumi's husband's older brother passed away. After five years apart, Hitomi suddenly reappears, reigniting their intense emotional and physical bond, forcing Kazumi into a deep inner conflict. A passionate, emotionally complex story unfolds as forbidden desires resurface between the two women.