College student Nao Kanzaki has always been, like her name, "extremely smart and honest"—so honest that people consider her foolish. But her life takes a drastic turn when she receives an unknown package containing 100 million yen. Without thinking, she opens it and unknowingly becomes part of the "Liar Game." This game has only one principle: deceive your partner and win millions of rupees, but if you lose, you will be burdened with debt for the rest of your life. When Nao sees darkness everywhere, she turns to a man who is a master of deception himself for help. That day, renowned fraudster Shinichi Akiyama is released from prison—a psychology student who single-handedly ruined an entire company. Initially, Shinichi doesn't want to get involved in this mess again, but seeing Nao's despair and passion, he agrees to help her. In this world of lies, Nao and Shinichi discover not only the truth of the game but also the dark secrets of human nature.