Well, the group is taken to an airport, where they meet Yokoya, the white-haired man, who asked to take part in the game (he was in another playing field).
The players are then told how the third game will work: in this game, players are split into two teams-water country and fire country. The purpose of this game is to smuggle money(which is actually you're own money) from the opposing country's bank. In order to do so, players from each team face of (30 times) in two rooms. The problem is, each player has been given 500 million yen, instead of the usual 100 million!
So, the players take their trunks, either filled in with money or empty to the room, where their opponent awaits them. If your opponent thinks the trunk is empty, he'll say 'Pass'. If he thinks it has money inside, he'll say 'Doubt', followed by the amount he thinks is inside the trunk, up to 100 million yen.
So, imagine Nao tries to steal 100 million from the Fire Bank. She goes there, takes the money, and puts it in her trunk. Yokoya then tries to stop her, by trying to guess the amount she has there. Assume he misses and passes. This means she manages to get the money, because the trunk is all but empty.
Now imagine he called for 50 million yen. She would still take the money because the amount she is trying to take is greater than the one he predicted.
Finally, if the trunk was empty (Nao didn't take any money from the bank) and Yokoya said 100 million, he'd have to pay half that amount.
Anyway, the Water team (Nao + Akiyama + Fukunaga + Oono + Hiromi) takes quite a beating in the beginning of the game because everyone is afraid of betting their money, whereas the fire country isn't.
Nevertheless, Akiyama manages to deceive one of the fire country players, meaning they can no longer rely on their 'pass' strategy. All was going well until Yokoya shows up.....He beats Oono and faces Nao. He asks her if she was the one who said that everyone could be happy in the Liar Game. She says she was indeed the one and he calls her stupid. He then goes on about how people who deceive others have a right to exploit them.
He then reveals he is actually a clairvoyant. Nao refuses to believe him and, to prove her wrong, he guess the amount on her trunk which was, as thought by Fukunaga, 51 million yen (up until that point only 3 patterns -doubt 100 million, doubt 50 million and pass - had emerged). He did that again with Fukunaha (52 million), all the while Oono says he found a sure-fire way to win ( it works), but isn't willing to let others in unless Fukunaga and everyone else call him 'Oono-sama'.