Housewife Keiko Natori lives happily with her elite banker husband, Shinichi. Her husband, best friend and little sister all support her. But on their first anniversary, Keiko sees a message on Shinichi's phone: "Last night was fun." The sender? Her best friend Yuka. It's only the beginning of a brutal battle driven by jealousy and desire. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

Keiko Natori begins to suspect her husband Shinichi of cheating with her best friend Yuka after seeing his phone. But it's actually her little sister Shiho, whom she trusts completely. Shiho lives to see her perfect sister miserable and has always stolen what mattered to her. Letting Shinichi marry Keiko was part of her plan to destroy her happiness. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

Keiko begins to suspect her husband Shinichi is cheating, never imagining the other woman is her sister Shiho. She accuses her best friend Yuka and loses her. While Shiho secretly smirks, Keiko learns she's pregnant with Shinichi's child. But as Shiho's twisted feelings grow, her attempt to destroy her sister's happiness leads to tragedy. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

Overjoyed by her pregnancy, Keiko falls down the stairs at a department store with her sister Shiho and miscarries. At the hospital, Shiho cries, blaming herself, but Keiko comforts her. Shiho is secretly pleased. Visiting Keiko, her friend Yuka clears the misunderstanding but hints at a new concern. Keiko's suspicion now turns to Shiho. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

"I'm in love with Shinichi," Shiho shocks her sister Keiko, who is blindsided and plunged into despair. Shiho smirks, wishing her more misery. Shinichi's desperate pleas go unheard. Retreating home, Keiko mourns alone. Encouraged by her friend Yuka, she resolves to face Shinichi and reclaim her happiness, but Shiho's next vicious move strikes. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

"I'm carrying Shinichi's child," Shiho shocks everyone at their parents' house. Her father lashes out at Shinichi. Watching her family break, Keiko declares, "I'm divorcing you." A month later, she lives alone in a small apartment, ready to restart, only for Shiho to strike. Keiko finally uncovers her sister's cruel nature and prepares to fight back. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

As Keiko starts her new life post-divorce, Shiho and Shinichi hold their wedding. Suddenly, the lights go out and the host announces a surprise guest. The doors open to reveal Keiko, looking stunning. Smiling and congratulating them, she receives applause, but her true aim is revenge. The time has come for Keiko to shatter Shiho's happiness. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

A year after Keiko ruined their wedding, Shiho and Shinichi's marriage is already failing. Exhausted by a crying baby and chores, Shiho is miserable. Meanwhile, Keiko, proposed to by her new love Haruki, can't fully rejoice. When Shiho reappears with her baby, Keiko smiles, determined to be happy, but Shiho is plotting to destroy her newfound joy. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

Keiko's fiance Haruki is falsely accused of groping by her sister Shiho. Keiko, humiliated, apologizes on her knees to save him. Heartbroken, she breaks off the engagement. Shiho smugly spreads the apology video, costing them jobs and ending their life together. But Keiko refuses to give up, her fierce revenge is about to begin. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

Three years after breaking off her engagement to Haruki, Keiko, now working at a restaurant, faces her sister Shiho, who flaunts her wealth. But Keiko's been waiting for this, plotting revenge with her friend Yuka. Shiho tries to undermine Keiko, but her menu wins acclaim. The final battle: sister seeking happiness versus sister bent on destruction. ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV

Promoted to restaurant manager, Keiko warns her sister Shiho not to interfere with the reopening. The next day, Shiho shows up to sabotage her, but Keiko reveals the opening isn't today, tricking her. Coldly, Keiko declares she will expose all Shiho's past misdeeds, shattering her happiness. The sisters' battle reaches its shocking final showdown! ©Saimasa • Takeno Takenoko • Mashiki ©NIPPON TV