The card reads as follows:
Congratulations! You are one of the 1 in 100,000 people who has been entered in the amazing LIAR GAME TOURNAMENT!

Along with the postcard there is 100 million yen in notes. That's the beginning of the Liar Game. When the game ends, in 30 days, you will have to return your 100 million. If your opponent steals them, he can keep them as a prize, and you will have a debt of 100 million...