Liar Game

Liar Game (2007) is a drama, crime with 2 seasons, rated 7.8/10.

Nao Kanzaki is a college student who is known for her honesty and naivete. One day, she receives a black postcard indicating that she has been selected to participate in the "Liar Game Tournament". Along with the postcard is a box with 100 million yen. The goal of the first round of the game is to trick the other player out of their hundred million yen. At the end, the winner would get to keep the hundred million earned, and the loser owes the LGT 100 million yen, which "will be collected by any means and at all costs".